Alarm:
A device that sounds a signal at a pre-set time. 

Altimeter:
A device that determines altitude by responding to changes in barometric pressure.

Analog Display:
A display that shows the time by means of hands and a dial.

Analog Watch:
Awatch with a dial, hands, and numbers or markers that present a totaldisplay of 12-hour time span. Analog digital refers to a watch that hasboth a digital display and hands of a conventional watch. 

Aperture:
Smallopening. The dials of some watches (in French: montres à guichet) haveapertures in which certain indications are given (e.g. the date, thehour, etc). 

Assembling:
Process of fittingtogether the components of a movement. This was formerly done entirelyby hand, but the operations have now been largely automated.Nevertheless, the human element is still primordial, especially forinspection and testing. 

Automatic Movement:
Amechanical movement that requires no winding because the rotor, part ofthe automatic mechanism, winds the mainspring every time you move yourhand. The first automatic movement was invented in Switzerland byAbraham-Louis Perrelet in the Eighteenth century. When fully wound andleft to sit, most automatics have up to 36 hours of reserve power.Mechanical movements are accurate within one minute each day. Automaticmovements have gained in popularity the last few years especially withwatch connoisseurs and are considered to be Switzerland’s mechanicalanswer to the popularity of the no-winding-needed quartz movements thatare standard in Japanese watches. 

Auto Repeat Countdown Timer:
Acountdown timer that resets itself as soon as the preset time haselapsed and starts the countdown again. It repeats the countdowncontinuously until the wearer pushes the stop button. 

Automatic Watch:
Awatch whose mainspring is wound by the movements or accelerations ofthe wearer’s arm. On the basis of the principle of terrestrialattraction, a rotor turns and transmits its energy to the spring bymeans of an appropriate mechanism. The system was invented inSwitzerland by Abraham-Louis Perrelet in the 18th century. 

Automatic Winding:
(alsocalled “self-winding”) Winding that occurs through the motion of thewearer’s arm rather than through turning the winding stem. It works bymeans of a rotor that turns in response to motion, thereby winding upthe watch’s mainspring. An automatic watch that is not worn for a day ortwo will wind down and need to be wound by hand to get it startedagain. 

Balance Spring:
A very fine spring(also called a “hair spring”) in a mechanical watch that returns thebalance 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. 

Battery Reserve Indicator:
See “power reserve indicator”. 

Bezel:
The ring, usually made of gold, gold plate or steel, that surrounds the watch face. 

Bi-directional Rotating Bezel:
Abezel that can be moved either clockwise or counterclockwise. These areused for mathematical calculations or for keeping track of elapsedtime. 

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. 

Cabochon:
Decorative stone which has been carved into a round shape. 

Calendar:
Afeature that shows the day of the month, and often the day of the weekand the year. There are several types of calendar watches. 

Caliber:
Aterm often used by Swiss watchmakers to denote a particular model type,such as Caliber 48 meaning model 48. More commonly, the term is used toindicate the movement’s shape, layout, or size. 

Cambered:
Often used in referring to a curved or arched dial or bezel. 

Case:
Themetal housing of a watch’s parts. Stainless steel is the most typicalmetal used but titanium, gold, silver, and platinum can also be used.Less expensive watches are usually made of brass and plated with gold orsilver. 

Caseback:
The reverse side of awatch case that lies against the skin. May be transparent to allowviewing of the inner workings of the watch or be solid. Mostmanufacturers engrave casebacks with their name, water and shockresistance, case metal content and other details. 

Chime:
Thebell-like sound made when a clock strikes on the hour, half hour, etc.Two familiar chimes traditionally found in clocks are the Westminsterchime made by the famous Big Ben in London. 

Chronograph:
Astopwatch, i.e., a timer that can be started and stopped to time anevent. There are many variations on the chronograph. Some operate with acenter seconds hand which keeps time on the watch’s main dial. Othersuse sub-dials to elapsed hours, minutes and seconds. Still others showelapsed time on a digital display on the watch face. When a chronographis used in conjunction with specialized scales on the watch face, it canperform many different functions, such as determining speed ordistance. Some chronographs can time more than one event at a time. Donot confuse the term “chronograph” with “chronometer”. The latter refersto a timepiece, which may or may not have a chronograph function, thathas met certain high standards of accuracy set by an official watchinstitute in Switzerland. Watches that include the chronograph functionare themselves called “chronographs”. 

Chronometer:
Thisterm refers to a precision watch that is tested in various temperaturesand positions, thus meeting the accuracy standards set by an officialinstitute in Switzerland. Most watch companies provide a certificatewith your chronometer purchase. 

Complication:
Awatch with other functions besides timekeeping. For example, achronograph is a watch complication. Other complications coveted bywatch collectors include: minute repeater, tourbillon, perpetualcalendar, or split second chronograph. 

COSC:
Theofficial Swiss Chronometer Testing Institute that puts everychronometer watch through a rigorous, 15-day testing procedure to verifythe watch’s precision. 

Countdown Timer:
Afunction that lets the wearer keep track of how much of a pre-set periodof time has elapsed. Some countdown timers sound a warning signal a fewseconds before time runs out — these are useful in events such as yachtraces, where the sailor must maneuver the boat into position before thestart of a race. 

Crown:
Button on theoutside 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 Buckle:
Atype of buckle that pops open and fastens using hinged, oftenadjustable, extenders. Though more expensive than a belt-buckle likeclosure, a deployment buckle is easier to put on and remove and is morecomfortable on the wrist. 

Depth Alarm:
Analarm on a diver’s watch that sounds when the wearer exceeds a pre-setdepth. In most watches it stops sounding when the diver ascends abovethat depth. 

Dial: The watch face. In high-endwatches the numerals, indices and surface designs are applied asseparate elements. In less expensive watches, they may be simply printedon the dial. 

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

Direct-drive:
Afunction that allows the second-hand to advance in intervals ratherthan a smooth sweep for more precise timekeeping. The French term for adirect-drive second hand is a trotteuse. 

Dual Timer:
Awatch that measures current local time as well as at least one othertime zone. The additional time element may come from a twin dial, extrahand, sub-dials, or other means. 

Elapsed Time Rotating Bezel:
Agraduated rotating bezel used to keep track of periods of time. Thebezel can be turned so the wearer can align the zero on the bezel withthe watch’s seconds or minutes hand. He/she can then read the elapsedtime off the bezel. This saves him/her having to perform the subtractionthat would be necessary if he used the watch’s regular dial. 

Engine Turning:
Decorative engraving, usually on the watch face. 

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

ETA:
Oneof the leading manufacturers of watch movements based in Switzerland.ETA movements are used by many major Swiss watch brands. 

Face: Thevisible side of the watch where the dial is contained. Most faces aremarked with Arabic or Roman numerals to indicate the hours.Interestingly, when Roman numerals are used, it is traditional to useIIII, rather than IV, to indicate the 4 o’clock position. 

Flyback hand:
Aseconds hand on the chronograph that can be used to time laps or todetermine finishing times for several competitors in race. 

Gasket:
Mostwater resistant watches are equipped with gaskets to seal the caseback, crystal, and crown to protect against water infiltration duringnormal wear. It is important to have the gaskets checked every two yearsto 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. 

Hard Metal:
Ascratch resistant metal comprised of binding several materials,including titanium and tungsten carbide, which are then pressed into anextremely hard metal and polished with diamond powder to addbrilliance. 

High-Tech Ceramic:
Used as aprotective shield for spacecraft reentering the earth’s atmosphere,high-tech ceramic is polished with diamond dust to create a highlypolished finish. Because the ceramic can be injection molded, pieces canbe contoured. It has a very smooth surface and is usually found inblack, but can be produced in a spectrum of colors. 

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.

Lap Memory:
Theability, in some quartz sport watches, to preserve in the watch’smemory the times of laps in a race that have been determined by the laptimer. The wearer can recall these times on a digital display by pushinga button. 

Lap Timer:
A chronograph functionthat lets the wearer time segments of a race. At the end of a lap,he/she stops the timer, which then returns to zero to begin timing thenext lap. 

Limited Editions:
A watch stylemanufactured in a specific amount, often numbered, and available inlimited quantities. Limited editions are available from most fine watchmanufacturers and may be highly prized by collectors. 

Liquid-Crystal Display:
Adigital watch display that shows the time electronically by means ofthe liquid held in a thin layer between two transparent plates. 

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 Wind:
Amanual wind watch must be wound every day by the crown in order to run.Even with that inconvenience, they are still produced by the majorhouses in Switzerland. Some of the most beautiful pieces made today aremanual wind, and you actually won’t fund many value or budget manualwinds (but they exist!). With exhibition backs becoming very common,it’s nice to view the active movement without a rotor in the way.

Marine Chronometer:
Highlyaccurate mechanical or electronic timekeeper enclosed in a box (hencethe term box chronometer), used for determining the longitude on boardship.Marine chronometers with mechanical movements are mounted ongimbals so that they remain in the horizontal position is necessary fortheir precision. 

Measurement Conversion:
Afeature, 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 kilograms. 

Mechanical Movement:
Amovement based on a mainspring which is wound by hand; when wound, itslowly unwinds the spring in an even motion. An automatic mechanicalrequires no winding because of the rotor, which winds the mainspringevery time you move your wrist.

Micron:
Unit of measurement of the thickness of the gold-coating. 1 micron = 1/1000mm. 

Military or 24-hour time:
Whentime is measured in 24-hour segments. To convert 12-hour time into24-hour, simple add 12 to any p.m. time. To convert 24-hour time into12-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:
Iridescentmilky interior shell of the freshwater mollusk that is sliced thin andused on watch dials. While most have a milky white luster,mother-of-pearl also comes in other colors such as silvery gray, grayblue, pink and salmon. 

Movement:
The innermechanism of watch that keeps time and moves the watch’s hand, calendar,etc. Movements are either mechanical or quartz. 

Mystery Watch:
Apatented invention of watchmaker Vincent Calabrese and produced by JeanMarcel, a Swiss manufacturer, the Mystery automatic mechanical watchuses no hands to indicate hours, minutes or seconds. Rather a jumpinghour window moves clockwise around a minute scale while a secondindicator, an arrow, also ticks around. Gently breathing on the crystalcauses the word “mystery” to appear. 

Pedometer:
A device that counts the number of strides taken by the wearer by responding to the impact of the wearer’s steps. 

Perpetual Calendar:
Acalendar that automatically adjusts for the months’ varying length andfor leap year. Perpetual calendars, which can be powered by quartz ormechanical movements, are programmed to be accurate until the year 2100.Many watch collectors suggest storing mechanical versions in motorizedwinding boxes when they aren’t being worn in order to maintain thecalendar countdown. 

Platinum
One of therarest of precious metals, platinum also is one of the strongest andheaviest, making it a popular choice for setting gemstone jewelry andwatches. It has a rich, white luster, and an understated look. Platinumis hypoallergenic and tarnish resistant. Platinum used in jewelry andwatches is at least 85 to 95 percent pure. Many platinum watches areproduced in limited editions due to the expense and rarity of themetal. 

Power Reserve
The amount of energyreserve stored up to keep a watch running until it stops. The remainingpower 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. 

Pulsimeter:
A scale on a chronograph watch for measuring the pulse rate. 

Push-piece:
Button that is pressed to work a mechanism. (The push-pieces on chronographs, striking watches, alarms, etc.) 

Quartz Crystal:
A tiny piece of synthetic quartz that oscillates at the rate of 32.768 times a second, dividing time into equal segments. 

Quartz Movement:
Amovement which allows a watch to keep time without being wound. Thistechnology employs the vibrations of a tiny crystal to maintain timingaccuracy. The power comes from a battery that must be replaced aboutevery 1.5 years. In recent years, new quartz technology enables thewatch to recharge itself without battery replacement. This power isgenerated via body motion similar to an automatic mechanical watch, orpowered by light through a solar cell, or even by body heat. A digitalquartz watch has no mechanical parts. Most quartz movements are made inHong Kong, Japan or Switzerland. 

Repeater:
A device that chimes the time when the wearer pushes a button. 

Rose (or pink) Gold:
Asoftly hued gold that contains the same metals as yellow gold but with ahigher concentration of copper in the alloy. A popular color in Europe,rose gold in watches is often seen in retro styling or in tricolor goldversions. Some 18k red gold watches achieve their color from additionalcopper in the alloy. 

Rotating Bezel:
Abezel (the ring surrounding the watch face) that can be turned.Different types of rotating bezels perform different timekeeping andmathematical functions. 

Rotor:
The part of an automatic watch that winds the the movement’s main spring. 

Sapphire Crystal:
Acrystal (the cover that protects the watch face) made of syntheticsapphire, 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:
Anadditional dial that can be set to the time in another time zone. Itlets the wearer keep track of local time and the time in another countrysimultaneously. 

Shock Absorber:
Resilientbearing which, in a watch, is intended to take up the shocks received bythe balance staff and thus protects its delicate pivots from damage. 

Shock Resistance:
Asdefined by the US government regulation, a watch’s ability to withstandan impact equal to that of being dropped onto wood floor from a heightof 3 feet. 

Skeleton Case:
A case with a transparent front or back that allows the wearer to view the watch’s movement. 

Slide Rule:
Adevice, consisting of logarithmic or other scale on the outer edge oftheir watch face , that can be used to do mathematical calculations. 

Solar Compass: Acompass that lets the wearer determine the geographical poles by meansof a rotating bezel. The wearer places the watch so that the hour handfaces the sun. He then takes half the distance between the position and12 o’clock, and turns the bezel until its “south” marker is at thathalfway point. Some quartz watches have solar compasses that showdirections on an LCD display. 

Solar Powered Batteries:
Batteries in a quartz watch that are recharged via solar panels on the watch face. 

Split Seconds Hand:
Actuallytwo hands, one a flyback hand the other a regular chronograph hand.When the wearer starts the chronograph, both hands move together. Totime laps or different finishing times, the wearer can stop the flybackhand independently while the regular chronograph hand keeps moving, ineffect”splitting” the hand(s) in two. 

Stainless Steel:
Anextremely durable metal alloy (chromium is a main ingredient) that isvirtually immune to rust, discoloration and corrosion; it can be highlypolished, thus representing a precious metal. Due to this and theimportance of white metal jewelry, steel has become a popular settingfor diamonds. Because of its strength, stainless steel is often usedeven on casebacks of watches made of other metals. 

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

Sterling Silver:
Awhite and highly reflective precious metal. Sterling silver refers tosilver that is 92.5 percent pure, which should be stamped on the metal,sometimes accompanied by the initials of the designer or the country oforigin as a hallmark. Although less durable than stainless steel andother precious metals, sterling silver is often employed in watches thatcoordinate or look like sterling silver jewelry. A protective coatingmay be added to prevent tarnishing. 

Stopwatch:
Awatch with a seconds hand that measures intervals of time. When astopwatch is incorporated into a standard watch, both the stopwatchfunction and the timepiece are referred to as a “chronograph”. Sub-dial:A small dial on the watch face used for any of several purposes, suchas keeping track of elapsed minutes or hours on the chronograph orindicating 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 Origin):
A mark identifying a watch that is assembled in Switzerland with components of Swiss origin. 

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:
Arectangular watch designed by Louis Cartier. The bars along the sidesof the watch were inspired by the tracks of tanks used in World War I. 

Telemeter:
Atelemeter determines the distance of an object from the observer bymeasuring how long it takes sound to travel that distance. Like atachymeter, it consists of a stopwatch, or chronograph, and a specialscale, usually on the outermost edge of the watch face. 

30-Minute Recorder:
(or register): A sub-dial on a 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:
The“space age” metal, often used with a silver-gray appearance. Because itis 30 percent stronger and nearly 50 percent lighter than steel it hasbeen increasingly used in watchmaking, especially sport watch styles.Its resistance to salt water corrosion makes it particularly 
usefulin diver’s watches. Since it can be scratched fairly easy, somemanufacturers use a patented-coating to resist scratching.Hypoallergenic. 

Tonneau Watch:
A watch shaped like a barrel, with two convex sides. 

Totalizer:
A mechanism that keeps track of elapsed time and display it, usually on a sub-dial. 

Tourbillon:
Adevice in a mechanical watch that eliminates timekeeping errors causeby the slight difference in the rates at which a watch runs in thehorizontal and vertical positions. The Tourbillon consist of roundcarriage, or cage, holding the escapement and the balance. It rotatescontinuously at the rate of once per minute. 

Tritium:
Anisotope of hydrogen that is used to activate the luminous dots orindices on a watch dial. The radioactivity released in this process istoo slight to pose a health risk. 

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 sub-dial on a chronograph that can time periods of up to 12 hours. 

Uni-directional Rotating Bezel:
Anelapsed time rotating bezel, often found on divers’ watches, that movesonly in a counterclockwise direction. It is designed to prevent a diverwho has unwittingly knocked the bezel off its original position fromoverestimating his remaining air supply. Because the bezel moves in onlyone direction, the diver can error only on the side of safety whentiming his dive. Many divers’ watches are ratcheted, so that they lockinto place for greater safety. 

Vibration:
Movementof a pendulum or other oscillating element, limited by two consecutiveextreme positions. The balance of a mechanical watch generally makesfive or six vibrations per second (i.e. 18,000 or 21,600 per hour), butthat of a high-frequency watch may make seven, eight or even tenvibrations 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:
Awater resistant watch can handle light moisture, such as a rain or sinksplashes, but should not be worn swimming or diving. If the watch canbe submerged in water, it must state at what depth it maintains waterresistance, i.e. 50 meters or more on most sport watches. Below 200meters, the watch may be used for skin diving and even scuba divingdepending upon the indicated depths. 

White Gold:
Createdfrom yellow gold by incorporating either nickel or palladium to thealloy to achieve a white color. Most watches made of white gold will be18k. 

Winding:
Operation consisting intightening the mainspring of a watch. This can be done by hand (by meansof the crown) or automatically (by means of a rotor, which is caused toswing 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:
Adial, usually on the outer edge of the watch face, that tells the timeup to 24 time zones around the world. The time zones are represented bythe names of cities printed on the bezel or dial. The wearer reads thehour in a particular time zone by looking at the scale next to the citythat 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 that sounds warning signals during the countdown to a boat race. 

Yellow Gold:
Thetraditionally popular gold used in all gold, gold and stainless steel,or other precious metal combinations. Yellow gold watches may be foundin 14k or, as found from most European manufacturers, 18k.