Alarm : A device that sounds a signal at a pre-set time.
Analog Display: A display that shows the time by means of hands and a dial.
Analog Watch: A watch with a dial, hands, and numbers or markers that present a total display of 12-hour time span. Analog digital refers to a watch that has both a digital display and hands of a conventional watch.
Aperture: Small opening. The dials of some watches (in French: montres à guichet) have apertures in which certain indications are given (e.g. the date, the hour, etc).
Automatic Movement: A mechanical movement that requires no winding because the rotor, part of the automatic mechanism, winds the mainspring every time you move your hand.
Automatic Winding: (also called "self-winding") An Automatic watch operates with the same principle as a mechanical manual wind watch - with the addition of a weighted pendulum called the "Rotor". The Rotor is attached to the back of the movement, and when the watch is in motion (with regular wear) the rotor spins around the inside of the watch & "automatically" winds the watch, thus eliminating the need to constantly manually wind the watch. It is important to understand that automatic watches also require a manual wind every so often. An automatic watch that has stopped or is at the end of its power reserve due to non-wear should be manually wound 20-30 times. Manually winding an automatic watch after the power reserve has ebbed or the watch has stopped ensures the watch is at full reserve when first worn, so as long as the watch is worn it will remain fully wound.
Balance Spring: A very fine spring (also called a "hair spring") in a mechanical watch that returns the balance wheel back to a neutral position.
Balance Wheel: The part of a mechanical watch movement that oscillates, dividing time into equal segments.
Barrel: Thin cylindrical box containing the mainspring of a watch. The toothed rim of the barrel drives the train.
Bezel: The ring, usually made of gold, gold plate or steel, that surounds the watch face.
Bi-directional Rotating Bezel: A bezel that can be moved either clockwise or counterclockwise. These are used for mathematical calculations or for keeping track of elapsed time.
Bracelet: A type of watch band made of elements that resemble links.
Bridge: Complementary part fixed to the main plate to form the frame of a watch movement. The other parts are mounted inside the frame.
Calendar: A feature that shows the day of the month, and often the day of the week and the year. There are several types of calendar watches.
Calibre: A term often used by Swiss watchmakers to denote a particular model type, such as Caliber 48 meaning model 48. More commonly, the term is used to indicate the movement's shape, layout, or size.
Cambered: Often used in referring to a curved or arched dial or bezel.
Case: The metal housing of a watch's parts. Stainless steel is the most typical metal used but titanium, gold, silver, and platinum can also be used. Less expensive watches are usually made of brass and plated with gold or silver.
Caseback: The reverse side of a watch case that lies against the skin. May be transparent to allow viewing of the inner workings of the watch or be solid. Most manufacturers engrave casebacks with their name, water and shock resistance, case metal content and other details.
Chime: The bell-like sound made when a clock strikes on the hour, half hour, etc. Two familiar chimes traditionally found in clocks are the Westminster chime made by the famous Big Ben in London, and the bim bam, a two note chime.
Chronograph: A stopwatch, 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 subdials to elapsed hours, minutes and seconds. Still others show elapsed time on a digital display on the watch face. 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. Some chronographs can time more than one event at a time. 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. Watches that include the chronograph function are themselves called "chronographs".
Chronometer: This term refers to a precision watch that is tested in various temperatures and positions, thus meeting the accuracy standards set by an official institute in Switzerland. Most watch companies provide a certificate with your chronometer purchase.
Complication: A watch with other functions besides timekeeping. For example, a chronograph is a watch complication. Other complications coveted by watch collectors include: minute repeater, tourbillon, perpetual calendar, or split second chronograph.
COSC: The official Swiss Chronometer Testing Institute that puts every chronometer watch through a rigorous, 15-day testing procedure to verify the watch's precision.
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 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: Button on the outside of the case that is used to set the time and the calendar, and, in the mechanical watches, to wind the mainspring.
Crystal: The transparent cover on the watch face made of glass crystal, synthetic sapphire or plastic.
Day/Date Watch: A watch that indicates not only the date but also the day of the week.
Day/Night Indicator: A colored or shaded band on a world time that shows which time zones are in daylight and which in darkness.
Deployment (Deployant) Buckle: A type of buckle that pops open and fastens using hinged, often adjustable, extenders. Though more expensive than a belt-buckle like closure, a deployment buckle is easier to put on and remove and is more comfortable on the wrist.
Dial: The watch face. In high-end watches the numerals, indices and surface designs are applied as separate elements. In less expensive watches, they may be simply printed on the dial.
Digital watch: A watch that shows the time through digits rather than through a dial and hands display.
Dual Timezone: 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 used to keep track of periods of time. The bezel can be turned so the wearer can align the zero on the bezel with the watch's seconds or minutes hand. He/she can then read the elapsed time off the bezel. This saves him/her having to perform the subtraction that would be necessary if he used the watch's regular dial.
Escapement: Device in a mechanical movement that controls the rotation of the wheels and thus the motion of the hands.
ETA: One of the leading manufacturers of watch movements based in Switzerland. ETA movements are used by many major Swiss watch brands.
Face: The visible side of the watch where the dial is contained. Most faces are marked with Arabic or Roman numerals to indicate the hours. Interestingly, when Roman numerals are used, it is traditional to use IIII, rather than IV, to indicate the 4 o'clock position.
Flyback hand: A seconds hand on the chronograph that can be used to time laps or to determine finishing times for several competitors in race.
Gasket: Most water resistant watches are equipped with gaskets to seal the case back, crystal, and crown to protect against water infiltration during normal wear. It is important to have the gaskets checked every two years to maintain the water resistance of the watch.
Gear Train: The system of gears which transmits power from the mainspring to the escapement.
Gold plating: A layer of gold that has been electro-deposited onto a metal; its thickness is measured in microns.
Grande Sonnerie: A type of repeater that sounds the hours and quarter hours when the wearer pushes the button.
Guilloche: A style of intricate engraving that is popular on watch dials, usually very thin lines interwoven to create a surface texture.
High-Tech Ceramic: Used as a protective shield for spacecraft reentering the earth's atmosphere, high-tech ceramic is polished with diamond dust to create a highly polished finish. Because the ceramic can be injection molded, pieces can be contoured. It has a very smooth surface and is usually found in black, but can be produced in a spectrum of colours.
Horology: The science of time measurement, including the art of designing and constructing the timepieces.
Index: An hour indicator on an analog watch dial, used instead of numerals.
Integrated Bracelet: A watch bracelet that is integrated into the design of the case.
Jewels: Synthetic sapphires or rubies that acts as bearings for gears in the mechanical watch, reducing friction.
Jump Hour Indicator: A jump hour indicator takes the place of an hour hand. It usually shows the hours by means of a numeral in a window.
Limited Editions: A watch style manufactured in a specific amount, often numbered, and available in limited quantities. Limited editions are available from most fine watch manufacturers and may be highly prized by collectors.
Lugs: Projection on the watch face to which the watch band/bracelet is attached.
Main Plate: Base plate on which all the other parts of a watch movement are mounted.
Mainspring: The driving spring of a watch or clock, contained in the barrel.
Manual Winding: A Manual watch operates by manually winding the crown which winds the mainspring in the barrel, thus powering the watch. Once wound it will stay working for the specified amount of time as indicated in your manual (generally 35-45 hours).
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.
Mechanical Movement: A movement based on a mainspring which is wound by hand; when wound, it slowly unwinds the spring in an even motion. An automatic mechanical requires no winding because of the rotor, which winds the mainspring every time you move your wrist.
Military or 24-hour time: When time is measured in 24-hour segments. To convert 12-hour time into 24-hour, simple add 12 to any p.m. time. To convert 24-hour time into 12-hour time, subtract 12 from any time 13 to 24.
Moon-phase: A window in a watch face that shows which phase the moon is.
Mother-of-Pearl: Iridescent milky interior shell of the freshwater 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.
Movement: The inner mechanism of watch that keeps time and moves the watch's hand, calendar, etc. Movements are either mechanical or quartz.
Perpetual Calendar: A calendar that automatically adjusts for the months' varying length and for leap year. Perpetual calendars, which can be powered by quartz or mechanical movements, are programmed to be accurate until the year 2100. Many watch collectors suggest storing mechanical versions in motorized winding boxes when they aren't being worn in order to maintain the calendar countdown.
Platinum: One of the rarest of precious metals, platinum also is one of the strongest and heaviest, making it a popular choice for setting gemstone jewellery and watches. It has a rich, white luster, and an understated look. Platinum is hypoallergenic and tarnish resistant. Platinum used in jewellery 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.
Power Reserve: The amount of energy reserve stored up to keep a watch running until it stops. The remaining power is sometimes indicated by a small gauge on the dial.
Power Reserve Indicator: A feature of a mechanical watch that shows how much longer the watch will operate before it must be wound again.
Push-piece: A button that is pressed to work a watch function such as a chronograph, alarm or date corrector.
Quartz Movement: This is an electronic watch movement with a quartz crystal that oscillates when a current is applied to it. The power to run the watch is normally provided by a battery or a capacitor. A quartz movement is generally more accurate than a mechanical movement.
Repeater: A device that chimes the time when the wearer pushes a button.
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 colour in Europe, rose gold in watches is often seen in retro styling or in tricolour gold versions. Some 18k red gold watches achieve their colour 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.
Rotor: The part of an automatic watch that winds the the movement's main spring.
Sapphire Crystal: A crystal (the cover that protects the watch face) 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 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 Absorber: Resilient bearing which, in a watch, 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 the US goverment regulation, a watch's ability to withstand an impact equal to that of being dropped onto wood floor from a height of 3 feet.
Skeleton Case: A case with a transparent front or back that allows the wearer to view the watch's movement.
Split Seconds Hand: Actually two hands, one a flyback hand the other a regular chronograph hand. When the wearer starts the chronograph, both hands move together. To time laps or different finishing times, the wearer can stop the flyback hand independently while the regular chronograph hand keeps moving, in effect"splitting" the hand(s) in two.
Stainless Steel: An extremely durable metal alloy (chromium is a main ingredient) that is virtually immune to rust, discolouration and corrosion; it can be highly polished, thus representing a precious metal. Due to this and the importance of white metal jewellery, steel has become a popular setting for diamonds. Because of its strength, stainless steel is often used even on caseback of watches made of other metals.
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". Subdial: A small dial on the watch face used for any of several purposes, such as keeping track of elapsed minutes or hours on the chronograph or indicating the date.
Swiss Made: A watch is considered Swiss if its movement was assembled, started, adjusted and controlled by the manufacturer in Switzerland.
Swiss A.O.S.C. (Certificate of Orgin): A mark identifying a watch that is assembled in Switzerland with components of Swiss orgin.
Sweep Seconds-Hand: A seconds-hand that is mounted in the center of the watch dial.
Tachymeter: A device on the chronograph watch that measure 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 I.
Timer: Instrument used for registering intervals of time (durations, brief times), without any indication of the time of day.
Titanium: The "space age" metal, often used with a silver-gray appearance. Because it is 30 percent stronger and nearly 50 percent lighter than steel it has been increasingly used in watchmaking, especially sport watch styles. Its resistance to salt water corrosion makes it particularly useful in diver's watches. Since it can be scratched fairly easy, some manufacturers use a patented-coating to resist scratching. Hypoallergenic.
Tonneau Watch: A watch shaped like a barrel, with two convex sides.
Tourbillon: A device in a mechanical watch that eliminates timekeeping errors cause by the slight difference in the rates at which a watch runs in the horizontal and vertical positions. The tourbillon consist of round carriage, or cage, holding the escapement and the balance. It rotates continuously at the rate of once per minute.
Two Tone: A watch that combines two metals, usually yellow gold and stainless steel in the case of fine watches.
12-Hour Recorder (or Register): A subdial on a chronograph that can time periods of up to 12 hours.
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 error only on the side of safety 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).
Waterproof: An illegal and misused term. No watch is fully 100 percent waterproof.
Water Resistance: A water resistant watch can handle light moisture, such as a rain or sink splashes, but should not be worn swimming or diving. If the watch can be submerged in water, it must state at what depth it maintains water resistance, i.e. 50 meters or more on most sport watches. Below 200 meters, the watch may be used for skin diving and even scuba diving depending upon the indicated depths.
White Gold: Created from yellow gold by incorporating either nickel or palladium to the alloy to achieve a white color. Most watches made of white gold will be 18k.
Winding: Operation consisting in tightening the mainspring of a watch. This can be done by hand (by means of 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 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".
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.