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Watch Dictionary


watches terms

12-hour (24-hour) recorder (or register) A sub-dial on a chronograph that can time periods of up to 12 or 24 hours.
24-hour Indicator Displays military time by sub-wheels or digital readout.
30-minute recorder (or register) A sub-dial on a chronograph that can time periods of up to 30 minutes.


Alarm The watch alerts you with beeps at a pre-set time.
Alloy Combination of two or more pure molten metals. Generally, an alloy is given the name of the dominant metal.
Altimeter A device that determines altitude by responding to changes in barometric pressure.
Analog A watch that shows the time using hour and minute hands.
Annual calendar The feature that refers to a mechanical watch. It automatically adjusts months with 30 or 31 days and needs to be manually corrected when February turns into March. Thus it needs to be corrected once a year, which is why the calendar is called annual.
Anti-magnetic The movement of a mechanical watch can be thrown off balance if it comes in contact with a strong magnetic field; Magnetism is common in loudspeakers, televisions, refrigerators, cars, etc. etc. and these days most watches claim to be anti-magnetic. This is achieved by using alloys for certain parts, among them the balance wheel and escape wheel. Electronic watches are not susceptible to magnetism.
Aperture A small opening in the dial. In an aperture watch, various indications such as the month, moon phase, day, date, hour, minute, etc. are visible through these openings.
Atomic watches The watch can receive signals from six atomic clock radio broadcasts worldwide providing unerring timekeeping.The U.S. government operates an “Atomic Clock” in Boulder, CO. This Atomic Clock will not gain or lose a second in 60 million years.
Automatic movement (or self-winding) This term refers to a watch with a mechanical movement (as opposed to a quartz or electrical movement). The watch is wound by the motion of the wearer's arm rather than through turning the winding stem. A rotor that turns in response to motion winds the watch's mainspring. If an automatic watch is not worn for a day or two, it will wind down and need to be wound by hand to get it started again.


Baguette Ladies style watch with a thin, elongated face; usually rectangular in shape but may be oval.
This is essentially and oscillator which regulates
the speed of the movement of a mechanical watch.

A device that transform the energy created by a chemical reaction into electrical energy. Typically, a battery lasts for two to five years. Its lifespan will depend on the type of watch, its size and the amount of energy required for the different functions. A chronograph will consume more energy than a watch that shows only hours, minutes and seconds.

Special lithium-iodine batteries have a theoretical lifespan of 10 years.

Battery reserve indicator Some battery operated watches have a feature that indicates when the battery is approaching the end of its life. This is often indicated by the second hand moving in two second intervals instead of each second.
Barometer A feature found on some watches, measures the atmospheric pressure.
Bezel The ring which surrounds the watch dial (or face). The bezel is usually made of gold, gold plate or stainless steel.
Bi-directional rotating bezel A bezel that can be rotated either clockwise or counterclockwise. These are used for mathematical calculations such as average speed or distance or for keeping track of elapsed time
Built-in illumination Lighting on a watch dial that allows the wearer to read the time in the dark.
Buckle Usually matching the case, it attaches the two parts of the leather strap around the wrist.
Bow Variously-shaped ring for suspending a pocket watch and fastening a chain.Bow Watches
Bridge Complementary part fixed to the main plate to form the frame of a
watch movement. The other parts are mounted inside the frame.


Cabochon Decorative stone which has been carved into a round shape. Cabochon watch term
Ceramic From the Greek keramos meaning fired pottery. In watchmaking, ceramic is a high-tech material, generally made from aluminium and zirconium oxides (polycrystals) for the manufacturing of cases and decorative elements.
Calendar A feature that shows the date, and often the day of the week. There are several types of calendar watches. Most calendar watches show the information digitally through an aperture on the watch face. Some chronograph watches shoe the information on sub-dials on the watch face.
Caliber A watch movement or name of watches.

The case of a watch must not only protect the mechanism
and hold all the parts together but it must also look good sometimes
to the extent of making a timepiece into a piece of jewellery. A watch case is generally in 3 parts:

  • the bezel, which holds the crystal,
  • the band or centrepart, which contains the movement,
  • and the back, either snapped or screwed on, in to which, sometimes, is fitted a crystal so that an intricate mechanical movement watch

    case watches term
Case materials Materials range from inexpensive cast metal through molded plastic to solid chunks of steel or gold from which the case is machined. In Great Britain, gold cases are usually 18k, but less expensive watches are 9k. In most other countries, 14k is preferred. Caratage indicates the gold content of metal, stated as the number of parts of gold in every 24 parts, i.e. 18k gold is 18 parts of gold alloyed with six parts of metal. Platinum is becoming increasingly popular, as is titanium for its lightness. Ceramic cases and bracelets a scratch resistant space age material formed under great pressure and heat from powder are used by some manufacturers. It does not bear any resemblance to the ceramics used in pottery. Some watches in the middle price ranges are gold plated over brass -9k or 18k plating usually. Vermeil is the term used to describe silver which has been gold plated.
Centre seconds Seconds indicated by a hand at the centre of the dial, along with the hour and minute hands
Co-axial escapement Is a type of modern watch escapement mechanism invented by English watchmaker George Daniels. Considered by many to be one of the most significant horological advancements since the invention of the lever escapement, the co-axial escapement functions with virtually no lubrication thereby eliminating one of the shortcomings of the traditional lever escapement.
Chapter ring The ring on the watch dial bearing figures and minute marks. The hour figures are sometimes called chapters
Coral The skeleton of a marine animal. Coral polyps secrete a strong calcium structure that was often used for watch dials. It s colour ranges from pale pink (called angelskin coral) to orange to red to white to black. Coral has a hardness of about 3.5 and a specific gravity of 2.6 to 2.7.
Chronograph A watch that includes a built in stopwatch function - i.e., a timer that can be started and stopped to time an event. There are many variations on the chronograph. Some operate with a center seconds hand which keeps time on the watch's main dial. Others use sub-dials to time elapsed hours, minutes and seconds. Still others show elapsed time on a digital display on the watch face. Some chronographs can be used as a lap timer (see "flyback hand" and "split seconds hand"). The accuracy of the stopwatch function will commonly vary from 1/5th second to 1/100th second depending on the chronograph. Some chronographs will measure elapsed time up to 24 hours. Watches that include the chronograph function are themselves called "chronographs." When a chronograph is used in conjunction with specialized scales on the watch face it can perform many different functions, such as determining speed or distance (see "tachymeter" and "telemeter") Do not confuse the term "chronograph" with "chronometer." The latter refers to a timepiece, which may or may not have a chronograph function, that has met certain high standards of accuracy set by an official watch institute in Switzerland.
Chronometer Technically speaking, all watches are chronometers. But for a Swiss made watch to be called a chronometer, it must meet certain very high standards set by the Swiss Official Chronometer Control (C.O.S.C.). If you have a Swiss watch labeled as a chronometer, you can be certain that it has a mechanical movement of the very highest quality
Clasp The attachment used to connect the two ends of the watch bracelet or strap around the wrist.

There are a number of clasp types commonly used by the watch industry. The most common include:

Deployment Buckle: (also known as a fold-over buckle): Three-folding closure that secures two ends of a bracelet. When closed, the buckle covers the folding mechanism.

Push-Button Foldover Clasp With Safety: is a deployment clasp with a push-button mechanism that opens the bracelet, along with a fold over closure on top that provides a second layer of security.

Hidden Clasp: (also called butterfly clasp): Folds the sections under the watch band to make the bracelet appear as an uninterrupted chain.

Tang or Buckle Clasp: A buckle with a hook, the tang that fits into a hole on the watch strap

Jewelry Clasp: A hinged hook that folds over a bar to secure the watch band.

Compass A compass that lets the wearer determine the geographical poles by means of a rotating bezel.  The wearer places the watch so that the hour hand faces the sun.  He then takes half the distance between the position and 12 o'clock, and turns the bezel until its "south" marker is at that halfway point.  Some quartz watches have solar compasses that show directions on an LCD display.
Complications One or more features added to a watch in addition to its usual time-telling functions, which normally not only include the hours, minutes and seconds but also date and often the day of the week as well. Complications such as: perpetual calendars, moonphase displays, alarms, thermometer, Compass, Barometer, repeating mechanisms, quarter strikes as well as stop/start chronograph functions. Power reserve indicators are also usually regarded as 'complications'
Cosmograph The cosmograph differs to the chronograph in that the tachymeter is on the bezel rather than on the outer rim of the dial. This was invented by Rolex to create a more modern look to the watch.
Countdown timer A function that lets the wearer keep track of how much of a pre-set period of time has elapsed. Some countdown timers sound a warning signal a few seconds before the time runs out. These are useful in events such as yacht races, where the sailor must maneuver the boat into position before the start of a race.
Crown Also called a stem or pin, a crown is the button on the outside of the watch case that is used to set the time and date. In a mechanical watch the crown also winds the mainspring. In this case it is also called a "winding stem". A screw in (or screw down) crown is used to make a watch more water resistant. The crown actually screws into the case, dramatically increasing the water-tightness of the watch.
Crystal The transparent cover on a watch face made of mineral glass crystal, synthetic sapphire or plastic. Better watches often have a sapphire crystal which is highly resistant to scratching or shattering.


Dauphine Hands A wide, tapered hand with a facet at the center running the length of the hand.
Day/Night Indicator A colored or shaded band on a world time that shows which time zones are in daylight and which in darkness.
Depth alarm An alarm on a divers' watch that sounds when the wearer exceeds a pre-set depth
Depth sensor A device on a divers' watch that determines the wearer's depth by measuring water pressure. It shows the depth either by analog hands and a scale on the watch face or through a digital display.
Dial The watch face.
Digital watch A watch that shows the time through digits rather than through a dial and hands (analog) display.
Diamond Diamond is the hardest and most luminous precious stone. The price of a diamond is calculated according to the 4C criteria: Cut - Carat - Clarity - Color. The weight of a diamond is expressed in carat: 1 carat is equal to 0.20 gram.
Pure colorless carbon, in jewelry the diamond is cut into facets to increase its sparkle. In watchmaking it is used to decorate straps, cases, bezels, etc.
Divers Watches Diver's watches are designed and manufactured especially for divers whose lives depend on the reliability of their watch in the water. Diver's watches must meet various standards regarding water resistancy, pressure resistancy, readability in the water, time presetting function (rotating elapsed time bezel), anti-magnetic ability, anti-shock, rust resistancy in salt water, manageability in water, ability to withstand sudden temperature changes, etc.
Dual Timer A watch that measures current local time as well as at least one other time zone. The additional time element may come from a twin dial, extra hand, subdials, or other means.


Elapsed time rotating bezel A graduated rotating bezel (see rotating bezel") used to keep track of elapsed time. The bezel can be turned so the wearer can align the zero on the bezel with the watch's seconds or minutes hand. After a period of time passes, you can read the elapsed time off the bezel. This saves you having to perform the subtraction that would be necessary if you used the watch's regular dial.
Electronic (quartz) watch A watch, usually battery-powered, which uses an electric current to cause a quartz oscillator to vibrate, normally 32,768 Hz per second but sometimes at much higher frequencies. These vibrations are processed by an integrated circuit which transforms the current into impulses. These are fed into a stepping motor which drives a train of gears to move the hands. Some quartz watches have solar cells which take light from any soul, natural or artificial, and transform them into electrical energy. Another form is the Seiko Kinetic (See Kinetic).
Emerald The saturated green variety of the Beryl family. Its color is due to minute traces of chromium or sometimes vanadium. Emeralds have a hardness of 7-8 and a specific gravity of 2.6 - 2.8.
Enamel A colored or transparent layer of vitreous material (i.e. a special type of glass) which protects or decorates its metal substrate.

Device in a mechanical movement that controls the rotation of the wheels and thus the motion of the hands. 


Flyback hand A seconds hand on a chronograph that can be used to time laps or to determine finishing times for several competitors in a race. Start the chronograph, putting both the flyback hand and the regular chronograph seconds hand in motion. To record a lap time or finishing time, stop the flyback hand. After recording the time, push a button and the hand will "fly back" to catch up with the constantly moving elapsed-time hand. Repeat the process to record as many lap times or finishing times as needed.
Fluorescence The ability of certain gemstones to transform invisible light (ultra violet light) into visible light (see Luminescence). Fluorite is such a mineral.


Gear train The system of gears which transmits power from the mainspring to the escapement.

Gold has seduced the world with its beauty, but also because not even acid can alter its natural properties. An estimated 130,000 tons have been extracted from the earth since prehistoric times, of which 100,000 tons in the twentieth century alone. Gold is a malleable substance (with a hardness of just 2.5) and therefore easy to work with. It can be used in an alloy with other metals, often silver and copper. These alloys increase its resistance and change its color.

Contains: For 750 gold, approximately:

Yellow gold: 12.5% silver - 75% pure gold - 12.5% copper

Pink gold: 6% silver - 19% copper - 60% pure gold - 10% palladium - 5% nickel

Red gold: 5.5 % copper - 94.5% pure gold

White gold: 10% copper - 10% palladium - 5% nickel - 75% pure gold

Blue gold: an alloy of gold and iron. Heat treatment oxidizes the iron molecules at the surface of the metal, producing the blue color.

Green gold: an alloy of gold, silver and copper.

Black gold: obtained by means of chemical vapor deposition (similar to PVD) of atoms of gold, carbon and other metals. The black coating is just a few microns thick. Other surface treatments use electrodeposition of rhodium, chromium and very dark impurities.

Brown gold: obtained by heat treatment.

Gold plated (Gilt) A layer of gold electroplated to a base metal.
Grande complications: The most complex of mechanical watches featuring an abundance of complications. The term is normally restricted to mechanical watches. Quartz watches with additional features are usually described as 'multi-functional'.
Grande Sonnerie A type of repeater that sounds the hours and quarter hours when the wearer pushes the button.
Guilloche A type of engraving in which thin lines are interwoven, creating a patterned surface.


Hard Metal A scratch resistant metal comprised of binding several materials, including titanium and tungsten carbide, which are then pressed into an extremely hard metal and polished with diamond powder to add brilliance.
Helium Escape Valve A helium escape valve is used in some divers watches, usually found at 10 o'clock on the watch case. If a diver is underwater for a long period of time, upon resurfacing the diver will open the escape valve to release the pressure built up in the watch. It is possible that without an escape valve the watch could damage or even explode. This is not a feature that is used very often, as the wearer would have to be under water for a long period of time.
Horology The science of measuring time.
Horn That part of a watch case to which the strap is attached. Horns come in various shapes and are attached to the case middle.
Hunter A watch whose case has a front and back cover.


Integrated bracelet A watch bracelet that is incorporated into the design of the case.


Jewels Synthetic sapphires or rubies that act as bearings for gears in a mechanical watch. The jewels reduce friction to make the watch more accurate and longer lasting.
Jumping hours System of timekeeping whereby the seconds and minutes are shown by traditional hands but the hour is shown in a dial cutout (often at 12), on the minutes hand reaching 59 minutes, the hour disc under the dial will jump to the next hour


Karat or K An indication of the purity of the metal used, expressed in the number of 1/24th of the pure metal used in the alloy. Metals such as gold are too soft in their pure state use in jewelry, so they are typically made into an alloy with other metals for strength. 24K (equal to 24/24ths) is pure metal. 18K is 18 parts pure metal mixed with 6 parts of other metals. That translates to 18/24=0.750, which is 75% pure, or 750 parts per thousand.
Kinetic Refers to the Seiko line of Kinetic watches. This innovative technology has a quartz movement that does not use a battery. Movement of your wrist charges a very efficient capacitor which powers the quartz movement. Once the capacitor is fully charged, mens models will store energy for 724 days without being worn. Ladies models store energy for 3-7 days. Of course, if the watch is worn every day the capacitor is continually recharged. The watch alerts you to a low capacitor charge when the seconds hand starts to move in two second intervals.


Lap timer A chronograph function that lets the wearer time segments of a race. At the end of a lap, he stops the timer, which then returns to zero to begin timing the next lap.
Light Emitting Diode (LED) A digital watch display showing time at the push of a button.
Liquid-crystal display (LCD) A digital watch display that shows the time electronically by means of a liquid held in a thin layer between two transparent plates. All LCD watches have quartz movements.
Lugs Projections on a watch face to which the watch band or bracelet is attached
Luminous Hands Hands made of skeleton form with the opening filled by a luminous material.
Luminescence Luminous dials first appeared during the Great War when soldiers needed to tell the time in the dark. Early forms used Zinc Sulphide compound agitated by a radioactive salt. It was painted on hands and was potentially dangerous to those applying it. Its use was banned in the 50's, since Tritium, a substance with a low radio activity, replaced it. Other methods have been devised. Timex's 'Indiglo' uses electronic luminescence; a button on the side of the case causes a tiny current from the battery to the electrodes and gives off energy in the form of light. Seiko uses fluorescent material on the dial, activated by any exposure to light.
LumiNova A new-generation luminous substance, used to coat hands and numerals. It stores light which it then emits in the dark causing the hands and numerals to glow and continue to be visible. Previously, radium salts were used which, because of their too dangerous radioactive properties, were replaced by Tritium and more recently by Super-LumiNova, a non-radioactive aloxide.


Manual A hand-wound mechanical watch. Wound by turning the crown back and forth until resistance is met.
Mainspring The driving spring of a watch or clock, contained in the barrel.mainspring watch term
Marine Chronometer Highly accurate mechanical or electronic timekeeper enclosed in a box (hence the term box chronometer), used for determining the longitude on board ship.Marine chronometers with mechanical movements are mounted on gimbals so that they remain in the horizontal position is necessary for their precision.
Mother-of-Pearl Iridescent, milky interior shell of the fresh water mollusk that is sliced thin and used on watch dials. While most have a milky white luster, mother-of-pearl also comes in other colors such as silvery gray, gray blue, pink, and salmon.
Measurement conversion A feature, usually consisting of a graduated scale on the watch's bezel, that lets the wearer translate one type of measurement into another-miles into kilometers, for instance, or pounds into kilogramsmeasurementConversion watches terms
Mechanical movement A movement powered by a mainspring, working in conjunction with a balance wheel. Most watches today have electronically controlled quartz movements and are powered by a battery. However, mechanical watches are currently enjoying a resurgence in popularity.
Minute repeater A watch which can additionally tell the time, at the push of a button or move of a small slide on the side of the case, by striking the hours, quarter hours and minutes since the last quarter hour on small goings inside the watch. Such complex watches are never inexpensive.
Moonphase display A graphic display by means of a specially shaped aperture in the dial to indicate the phase of the moon, i.e. full, new or somewhere in between. Very popular in the 90's but losing favour in the second half of the century.
Movement The inner mechanism of a watch that keeps time and moves the watch's hands, calendar, etc. Movements are either mechanical or quartz.


Natural pearl A natural pearl is also called an oriental pearl. This pearl is formed by an oyster, freshwater mussel or other mollusc as a reaction to a tiny invading object that happened to be caught inside its shell.


Organic Describes a substance produced by a living organism. Pearl, coral and shell are examples of organic substances used in jewellery.


Plexiglas A synthetic resin that can be used for watch crystal.
Power reserve indicator A feature that shows when the watch will soon need a new battery or winding. A battery reserve indicator on a quartz watch informs the wearer when the battery is low. Often this is indicated by the seconds hand moving at two or three-second intervals.
Pedometer A device that counts the number of strides taken by the wearer by responding to the impact of the wearer's steps.
Perpetual A type of calendar that automatically adjusts for months of different lengths and indicates February 29 in each leap year.
Platinum One of the rarest precious metals, platinum is also one of the strongest and heaviest, making it a popular choice for setting gemstone jewelry and watches. It has a rich, white luster, and an understated look. Platinum is hypoallergenic and tarnish resistant. Platinum used in jewelry and watches is at least 85 to 95 percent pure. Many platinum watches are produced in limited editions due to the expense and rarity of the metal.
Pushers or push pieces Push buttons are on the case of the chronographs and some complicated watches. Most are used to stop and start a stopwatch but sometimes serve other functions.
PVD - physical vapour deposition A coating of titanium nitrate applied in a vacuum and then covered by a coating of 22k gold to obtain a gold colored finish.


Quartz movement A movement powered by a quartz crystal to. Quartz crystals are very accurate. They can be mass produced which makes them less expensive than most mechanical movements which require a higher degree craftsmanship.


Rattrapante used to describe the split seconds chronograph (see Flyback) which has two seconds hands sitting atop one another. On depression of a third chronograph button (most have two), the flyback hand will stop in order to measure say, a lap time; repressing this button with cause the flyback hand to flyback(!) to the other seconds hand which has remained in motion.
Rose (or pink) Gold A softly hued gold that contains the same metals as yellow gold but with a higher concentration of copper in the alloy.  A popular color in Europe, rose gold in watches is often seen in retro styling or in tricolor gold versions.  Some 18k red gold watches achieve their color from additional copper in the alloy.
Rotating bezel A bezel (the ring surrounding the watch face) that can be turned. Different types of rotating bezels perform different timekeeping and mathematical functions (see elapsed time rotating bezel," "unidirectional rotating bezel," "bi-directional rotating bezel" and "slide rule.")
Rotor The part of an automatic (or self-winding) mechanical watch that winds the movement's mainspring. It is a flat piece of metal, usually shaped like a semicircle, that swivels on a pivot with the motion of the wearer's arm. rotor watches term


Sapphire crystal A crystal made of synthetic sapphire, a transparent, shatter-resistant, scratch-resistant (9 on the Moh scale) substance. A sapphire crystal is the material of choice for many watch collectors. The downsides are that sapphire can chip at the edges if they protrude and can shatter.
Screw-lock crown A crown that can be screwed into the case to make the watch watertight.
Second time-zone indicator An additional dial that can be set to the time in another time zone. It lets the wearer keep track of local time and the time in another country simultaneously.
Shock resistance As defined by U.S. government regulation, a watch's ability to withstand an impact equal to that of being dropped onto a wood floor from a height of 3 feet.
Skeleton watch A watch with no dial and only a chapter ring. As much metal is removed as possible and all the remaining parts are decorated with elaborate engravings.
Sliderule A device, consisting of logarithmic or other scales on the outer edge of the watch face, that can be used to do mathematical calculations. One of the scales is marked on a rotating bezel, which can be slid against the stationary scale to make the calculations. Some watches have slide rules that allow specific calculations, such as for fuel consumption by an airplane or fuel weight.
Solar powered A watch that uses solar energy (from any light source) to power the quartz movement. The Citizen >Solar-Tech< models use this technology and provide a 180 day power reserve, so they are able to run continuously. For more information, click here to go to Citizens Internet Site.
Spring bars (or pins) Spring-loaded bars between the lugs on the case, used to attach a strap or metal bracelet to the case.
Stepping motor: The part of a quartz movement that moves the gear train, which in turn moves the watch's hands
Sterling A white and highly reflective precious metal.  Sterling silver refers to silver that is 92.5 percent pure, which should be stamped on the metal, sometimes accompanied by the initials of the designer or the country of orgin as a hallmark.    Although less durable than stainless steel and other precious metals, sterling silver is often employed in watches that coordinate or look like sterling silver jewelry.  A protective coating may be added to prevent tarnish.
Strap/Bracelet Watches usually come fitted with either leather or rubber straps that close with a buckle or clasp, or a steel bracelet, that also secures with a clasp. Divers watches are usually fitted with steel bracelets or rubber straps to avoid corrosion.
Stopwatch A watch with a seconds hand that measures intervals of time. When a stopwatch is incorporated into a standard watch, both the stopwatch function and the timepiece are referred to as a chronograph
&Sub-dial A small dial on a watch face used for any of several purposes, such as keeping track of elapsed minutes or hours on a chronograph or indicating the date.
Swiss made As a part of a move towards greater consumer protection and in order to combat fakes in the Far East that claim to be swiss made, the Swiss federal council in 1993 laid down the rule that a watch has to satisfy before it could be described as swiss made. The movement must be of Swiss origin, and must contain at least 50% swiss parts. The watch must be cased in Switzerland and pass its final inspection in that country.


Tachymeter A feature found on some chronograph watches, a tachymeter (also called a "tachometer") measures the speed at which the wearer has traveled over a measured distance.
Tank watch A rectangular watch designed by Louis
Cartier. The bars along the sides of the watch were inspired
by the tracks of tanks used in World War 1.
Telemeter A telemeter determines the distance of an object from the observer by measuring how long it takes sound to travel that distance. Like a tachymeter (see "tachymeter"), it consists of a stopwatch, or chronograph, and a special scale, usually on the outermost edge of the watch face.
Thermometer A feature found on some watches, measures the temperature.
Titanium A metal that is used for some watch cases and bracelets. Titanium is much stronger and lighter than stainless steel. Titanium is also hypo-allergenic.
Tonneau watch A watch shaped like a barrel, with two convex sides.
Tourbillon A device, invented by Breguet in 1801, in which the escapement is mounted in a small revolving cage as a means of overcoming the effects of gravity on the precision on a mechanical timepiece.


Uni-directional rotating bezel An elapsed time rotating bezel, often found on divers' watches, that moves only in a counterclockwise direction. It is designed to prevent a diver who has unwittingly knocked the bezel off its original position from overestimating his remaining air supply. Because the bezel moves in only one direction, the diver can err only on the side of safety when timing his dive. Many divers' watches are ratcheted, so that they lock into place for greater safety.



Movement of a pendulum or oscillating body between two extreme positions. The balance of a mechanical watch generally makes five vibrations per second, equivalent to 18,000 vibrations/hour (2.5 Hz). A more accurate mechanical watch makes 10 vibrations per second or 36,000 vibrations/hour (5Hz).

A quartz watch makes 64,000 vibrations per second ( 32 MHz).

An oscillation ("tick-tock") equals two vibrations (although oscillation is sometimes incorrectly used to refer to a vibration).


Water resistance The ability to withstand splashes of water. Terms such as "water resistant to 50 meters" or "water resistant to 200 meters" indicate that the watch can be worn underwater to various depths.
Water Resistant - light rain or hand washing, but should not be used while swimming or diving.
    Water Resistant to 50M (165Ft.) - Suitable for showering or shallow water swimming
    Water Resistant to 100M (330Ft.) - Suitable for swimming or snorkeling.
    Water Resistant to 150M (500Ft.) - Suitable for snorkeling.
    Water Resistant to 200M (660Ft.) - Suitable for skin diving.
Sometimes water-resistance is measured in atmospheres (ATM). An ATM is equal to 10M of water pressure.
Winding stem The button on the right side of the watch case used to wind the mainspring. Also called a "crown."
World time dial A dial, usually on the outer edge of the watch face, that tells the time in up to 24 time zones around the world. The time zones are represented by the names of cities printed on the bezel or dial. The wearer reads the hour in a particular time zone by looking at the scale next to the city that the hour hand is pointing to. The minutes are read as normal. Watches with this feature are called "world timers."


Yacht timer A countdown timer (see "countdown timer") that sounds warning signals during the countdown to a boat race
Yellow Gold The traditionally popular gold used in all gold, gold and stainless steel, or other precious metal combinations.  Yellow gold watches may be found in 14k or, as found from most European manufacturers, 18k.