Alarm: A watch which alerts you with beeps at pre-set times.

Analog Digital Display: A watch that shows the time by means of hour and minute hands (analog display) as well as by numbers (a digital display).

Analog: A watch that shows the time using hour and minute hands.

Aperture: Small opening. The dials of some watches have apertures in which certain indications are given (e.g. the date, the hour, etc.)

Appliqué: Appliqué or applied chapters are numerals or symbols cut out of a sheet metal and stuck or riveted to a dial.

Assembling: Process of fitting together the components of a movement. This was formerly done entirely by hand, but the operations have now been largely automated. Nevertheless, the human element is still necessary, especially for inspection and testing.

Assortiment: French term for the parts used for making an escapement.

Automatic Winding (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.

Balance Staff: Moving part, usually circular, oscillating about its axis of rotation. The hairspring coupled to it makes it swing back and forth, dividing time into exactly equal parts. Each of the movements of the balance ("tick-tock") is called an "oscillation". One oscillation is composed of two vibrations.

Bar Lug: In wristwatch-cases, a thin metal rod fixed between the ends of the watch case for attaching the wrist bracelet.

Barrel: Thin cylindrical box containing the mainspring of a watch. The toothed rim of the barrel drives the train.

Battery Reserve Indicator (or End of Battery 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.

Bezel: The ring that 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 (see "elapsed time rotating bezel).

Bridge: Complementary part fixed to the main plate to form the frame of a watch movement. The other parts are mounted inside the frame (part of the "ébauche").

Built-in Illumination: Electro-luminscent lighting on a watch dial that allows the wearer to read the time in the dark.

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 show the information on sub-dials on the watch face.

Calibre (caliber): Originally used to mean the size of a watch movement, this term now denotes a type of movement (men's calibre, automatic calibre, etc.). When a calibre number is accompanied by the manufacturer's mark, it serves as an indication of origin.

Case: Container that protects the watch-movement from dust, damp and shocks. It also gives the watch as attractive an appearance as possible, subject to fashion and the taste of the public.

Casing (up): Process of inserting and fixing a watch movement into its case.

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 second 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.

Chablon: French term for a watch movement (not including the dial and hands), of which all or part of the components are not assembled.

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.

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: 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 glass crystal, synthetic sapphire or plastic. Better watches often have a sapphire crystal which is highly resistant to scratching or shattering.

Date: An ordinal number referring to a day of the month as in the 10th June.

Date-watch: A watch indicating the date, the month and sometimes the year and the phases of the moon. Also called a calendar-watch or calendar. A perpetual calendar watch indicates leap years as well as the date.

Depth Alarm: An alarm on a divers' watch that sounds when the wearer exceeds a pre-set depth.

Depth Sensor/Depth Meter: 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: Indicating "face" or plate of metal or other material, bearing various markings to show, in ordinary watches and clocks, the hours, minutes and seconds. Dials vary very much in shape, decoration, material, etc. The indications are given by means of numerals, divisions or symbols of various types.

Digital Watch: A watch that shows the time through digits rather than through a dial and hands (analog) display.

Direct-drive: Refers to a second hand that moves forward in little jerks. "Trotteuse" is the French term for a direct-drive second hand, especially a center second hand.

Display: Liquid-Crystal Display (LCD). Indication of time or other data, either by means of hands moving over a dial (analog display) or by means of numerals appearing in one or more windows (digital or numerical display). These numerals may be completed by alphabetical indications (alphanumerical display) or by signs of any other kind. Example: 12.05 MO 12.3 = 12 hours, 5 minutes, Monday 12th March. Such displays can be obtained by mechanical electronic means.

Diving Watch: A watch that is water resistant to 200 meters, has a one way rotating beze lwith a screw-on crown and case back along with a metal or rubber strap (not leather), a sapphire crystal and possibly a wet-suit extension.

Ebauche: French term (but commonly used in English-speaking countries) for a movement blank, i.e. an incomplete watch movement which is sold as a set of loose parts, comprising the main plate, the bridges, the train, the winding and setting mechanism and the regulator. The timing system, the escapement and the mainspring, however, are not parts of the "ébauche".

Elapsed Time Rotating Bezel: A graduated 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 calculate the elapsed time from the position on the bezel. This saves you having to perform the subtraction that would be necessary if you used the watch's regular dial.

Escapement: Set of parts (escape wheel, lever, roller) which converts the rotary motion of the train into back and forth motion (the balance).

Etablissage: French term for the method of manufacturing watches and/or movements by assembling their various components. It generally includes the following operations: receipt, inspection and stocking of the "ébauche", the regulating elements and the other parts of the movement and of the make-up; assembling; springing and timing; fitting the dial and hands; casing; final inspection before packing and dispatching.

Factory works: In the Swiss watch industry, the term manufacture is used of a factory in which watches are manufactured almost completely, as opposed to an "atelier de terminage", which is concerned only with assembling, timing, fitting the hands and casing.

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.

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

Gold plated: A layer of gold electroplated to a base metal.

Hand: Indicator, usually made of a thin, light piece of metal, very variable in form, which moves over a graduated dial or scale. Watches usually have three hands showing the hours, minutes and seconds.

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

Ionic Plating: A new method of plating which entails the combining and electrolysis of certain materials to look like gold plate, but containing no gold material and much more durable than gold plating.

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.

Kinetic: Refers to the Seiko line of Kinetic watches. This innovative technology has a quartz movement that does not use a battery. The movement of your wrist charges a very efficient capacitor which powers the quartz movement. Once the capacitor is fully charged, men's models will store energy for 7-14 days without being worn and 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.

Lugs: Projections on a watch case to which the watch band or bracelet is attached.

Main Plate: Base plate on which all the other parts of a watch movement are mounted (part of the "ébauche").

Mainspring: The driving spring of a watch or clock, contained in the barrel.

Manufacture d'horlogerie: French term for a watch factory which itself produces the components (particularly the "ébauches") needed for the manufacture of its products (watches, alarm and desk clocks, etc.).

Marine Chronometer: Highly accurate mechanical or electronic timekeeper enclosed in a box also referred to as a 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.

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. As an example; miles into kilometers, or pounds into kilograms.

Mechanical Movement: A movement powered by a mainspring, working in conjunction with a balance wheel. Most watches today have quartz movements and are powered by a battery. However, mechanical watches are currently enjoying a resurgence in popularity.

Movement: Assembly consisting of the principal elements and mechanisms of a watch or clock: the winding and setting mechanism, the mainspring, the train, the escapement, the regulating elements. The inner mechanism of a watch that keeps time and moves the watch's hands, calendar, etc. "Anatomically", the movement consists of the "ébauche", the regulating elements and the other components. Movements are either mechanical or quartz.

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. Seiko's Kinetic watches are quartz watches that do not have a battery (see Kinetic). When a Seiko Kinetic needs to be wound, the seconds hand will also move in two second intervals.

Quartz Movement: A movement powered by a quartz crystal. 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.

Rotating Bezel: A bezel is the ring surrounding the watch face that can be turned. Different types of rotating bezels will perform various timekeeping and mathematical functions (see elapsed time rotating bezel," "unidirectional rotating bezel," "bi-directional rotating bezel" and "slide rule.")

Regulating Elements: Set of parts comprising the regulating system (sprung balance) and the escapement (escape wheel, lever and roller).

Repeater: A watch that strikes the hours by means of a mechanism operated by a push-piece or bolt. There are various types of repeaters. Quarter-repeater sounds a low note for the hours and a "ding-dong" for each of the quarters. A five-minute repeater strikes the hours, quarters and five-minute periods after the quarter. A minute-repeater strikes the hours, quarters and minutes. The "Grande sonnerie" (grand strike) strikes the hours and quarters automatically and repeating when a push-piece is pressed down. A chiming repeater is the type where the quarters are struck on three or four gongs of different pitch.

Rotor: The part of an automatic (or self-winding) mechanical watch that winds the movement's mainspring. A half-disc of heavy metal, which is made to rotate inside the case of an automatic watch by the energy produced by the movements of the wearer's arm. Its weight tends always to bring it back to the vertical position. Demultiplied by a specially designed device, its rotations continually wind the mainspring of the watch.

Sapphire Crystal: A crystal made of synthetic sapphire, a transparent, shatter-resistant, scratch-resistant substance.

Screw-Lock Crown: A crown that can be screwed into the case to make the watch watertight.

Second: Basic unit of time, corresponding to one 86,000th part of the mean solar day, i.e. the duration of rotation, about its own axis, of an ideal Earth describing a circle round the Sun in one year, at a constant speed and in the plane of the Equator. After the Second World War, atomic clocks became so accurate that they could demonstrate the infinitesimal irregularities (a few hundredths of a second per year) of the Earth's rotation about its own axis. It was then decided to redefine the reference standard; this was done by the 13th General Conference on Weights and Measures in 1967, in the following terms: "The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the fundamental state of the atom of caesium 133". Conventionally, the second is subdivided into tenths, hundredths, thousandths (milliseconds), millionths (microseconds), thousand-millionths (nanoseconds) and billionths (picoseconds).

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.

Setting (to time): Process of bringing the hands of a watch or clock to the position corresponding to the exact time.

Shock Absorber: A resilient bearing which is intended to take up the shocks received by the balance staff and thus protects its delicate pivots from damage.

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 in which the case and various parts of the movement are of transparent material, enabling the main parts of the watch to be seen.

Slide Rule: 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 which enables the watch to run continuously.

Stepping Motor: The part of a quartz movement that moves the gear train, which in turn moves the watch's hands.

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.

Striking-Mechanism: In a watch or clock, an automatic or hand-operated mechanism that strikes the hours, etc., or rings an alarm-bell in a repeater watch.

Sub-Dial: A small dial on a watch face used for any of several purposes, such as keeping track of elapsed seconds, minutes or hours on a chronograph or indicating the date.

Swiss Watch: Only when it is Swiss, may a watch be marked "Swiss Made" or "Swiss", or any other expression containing the word "Swiss" or its translation, on the outside. According to Section 1a OSM, a watch is considered to be Swiss if its movement is Swiss, its movement is cased up in Switzerland and the manufacturer carries out the final inspection in Switzerland.

Tachymeter: Also called a "tachometer", it is a feature found on some chronograph watches. A tachymeter measures the speed at which the wearer has traveled over a measured distance. In watchmaking, a timer or chronograph with a graduated dial on which speed can be read off in kilometers per hour or some other unit (see timer).

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 either imprinted on the crystal ring on the inside of the case but usually on the top outside of the case.

Thirty Minute Recorder (or Register): A sub-dial on a chronograph (see "chronograph") that can time periods of up to 30 minutes.

Timer: Instrument used for registering intervals of time (durations, brief times), without any indication of the time of day.

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: Device invented to eliminate errors of rate in the vertical positions. It consists of a mobile carriage or cage carrying all the parts of the escapement, with the balance in the center of the watch. The escape pinion turns about the fixed fourth wheel. The case makes one revolution per minute, thus eliminating errors of rate in the vertical positions.

Twelve-hour (24-Hour) Recorder (or Register): A sub-dial on a chronograph (see chronograph) that can time periods of up to 12 or 24 hours.

Unidirectional Rotating Bezel: An elapsed time rotating bezel (see "elapsed time rotating bezel"), often found on divers' watches, that moves only counterclockwise . It is designed to prevent a diver who accidentally moved the bezel from its original position to overestimate his remaining air supply. Because the bezel moves in only one direction, the diver can still be safe when timing his dive. Many divers' watches are ratcheted, so that they lock into place for greater safety.

Vibration: Movement of a pendulum or other oscillating element, limited by two consecutive extreme positions. The balance of a mechanical watch generally makes five or six vibrations per second (i.e. 18,000 or 21,600 per hour), but that of a high-frequency watch may make seven, eight or even ten vibrations per second (i.e. 25,200, 28,800 or 36, 000 per hour).

Watch Material: Loose parts, components either for producing watches or for repairing them. In the latter case, they are often called "spare parts" or "repair material".

Water Resistance: Water-resistant cases have joints that are made to withstand splashes of water and prevent water from entering. 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.

Winding: An operation consisting of tightening the mainspring of a watch. This can be done by hand by means of turning the crown or automatically by means of a rotor, which is caused to swing by the movements of the wearer's arm.

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."