Alarm
Alarm functions may be fitted (most commonly) to battery powered quartz watches; the alarm with beep at the pre-set time. There are mechanical alarm watches featuring a hammer which produces the alarm sound at the pre-set time.

Amplitude
Sometimes used to describe the frequency of a mechanical movement, however seems more often used to describe the angle of oscillation of the balance wheel either side of its neutral position. This would therefore be measured in degrees, for example  'an amplitude of 270 degrees'.

Analogue: Analogue simply refers to the means of showing the time on a watch dial by means of hands which point to the hours, minutes and usually seconds.

Analog Digital
A watch that has both a digital display and hands of a conventional watch. Usually featured on sport watch styles.

Analog quartz
The most commonly-used term in referring to any analog timepiece that operates on a battery or on solar power and is regulated by a quartz crystal.

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)

Atmosphere (Atm)
Unit of pressure used in watch making to indicate water-resistance.

Auto repeat timer
A feature that allows for continuous operation of a countdown timer. If timer function is set at one hour and started, it will countdown to zero, beep with a warning signal and immediately return to the preset time and start the countdown again. This would continue until stop button is pushed.

Automatic movement
A movement that is all mechanical and requires no winding because the rotor, part of the automatic mechanism, winds the mainspring every time you move your hand. When fully wound and left to sit, most automatics will have up to 36 hours of reserve power. Mechanical movements are accurate within one minute each day.

B

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.
 

Balance-wheel
The regulating organ of the watch, vibrating on a spiral hairspring. Lengthening or shortening the balance-spring makes the balance-wheel go faster or slower to advance or retard the watch.

Bar/lug
A small rod with a sprung pivot at either end to fix the strap (band) to the case.

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

Base metal
Any non-precious metal.

Battery
Device that converts chemical energy into electricity. Most watch batteries are silver oxide type delivering 1.5 volts. Much longer-lasting lithium batteries are 3 volt.

Battery Life
The minimum period of time that a battery will continue to provide power to run the watch. Life begins at the point of manufacture when the factory initially installs the battery.

Bezel
The surface ring on the watch that surrounds and holds the crystal in place. A rotating ratchet bezel moves in some sport watches as part of the timing device. If rotating bezels are bi-directional, able to move clockwise or counter clockwise, they can assist in calculations for elapsed times.

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 (see "slide rule") or for keeping track of elapsed time(see "elapsed time rotating bezel").

Bracelet
Flexible metal band consisting of assembled links, usually in the same style as the case. detachable links change the length of the bracelet.

Brass
Copper and zinc alloy used to make the main plate and bridge wheels in the movement.

Buckle
Usually matching the case, it attaches the two parts of the leather strap around the wrist.

Button
Push piece controls, usually at 2 o'clock and/or 4 o'clock on the dial to control special functions such as the chronograph or the alarm.

C

Calendar
A watch feature that shows the date and sometimes the day of the week and the month. It can be displayed through a cut-out window in the dial, as a sud-dial with small hands indicating the day/date feature or by digital readout.

Calibre
The dimensions of the watch. Calibre describes the size and configuration of the movement and can now indicate the shape, origin and constructor as well.

Carat (Karat)
Unit of gold fineness (and gemstone weight). Pure gold is 24k. 18k gold is 75% pure.

Case
The metal housing of a watch's parts. Stainless steel is the most typical metal used but also titanium, gold, silver, and platinum can be used. Less expensive watches are usually made of brass and plated with gold or silver.

Chime : The bell-like sound made when a clock strikes on the hour, half hour, etc

Chronograph
A multifunction sport watch with a stopwatch function. Most have two or three sub dials, or minidials, for measuring minutes and hours.

Chronometer
A precision watch that is set in various temperatures and positions, thus meeting the accuracy standards set by an official watch institute in Switzerland. Most watch companies either provide this certificate with a purchase or it can be mailed to you.

Clasp
The attachment used to connect the two ends of the watch bracelet or strap around the wrist.

Countdown timer
Measures remaining time from preset period of time. (Example: Can be used to countdown time of a basketball game.)

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 clean cover over the watch face. Three types of crystals are commonly found in watches. Acrylic crystal, a plastic, is inexpensive and shallow scratches can be buffed out. Mineral crystal is comprised of several elements that are heat treated to create unusual hardness that aids in resisting scratches. Sapphire crystal is the most expensive and durable, approximately three times harder than mineral crystals and 20 time harder than acrylic crystals. A nonreflective coating on some sport styles prevents glare.

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.


D

Day/date watch
A watch that indicates not only the date but the day of the week.

Depth Alarm : An alarm on a diver's watch that sounds when the wearer exceeds a pre-set depth. In most watches it stops sounding when the diver ascends above that depth.

Dial
The watch face. The numerals, indices, or surface design are usually applied; others have been printed on.

Diachronic
A liquid-crystal display (LCD) enabling a color to appear or vanish on the surface.

Digital
Any watch that shows the time in numbers instead of hands on the dial. the numbers appear in LCD (liquid crystal diode) which shows a continuous reading or in LED (light-emitting diode) which shows time at the push of a button.

Digital Watch
A mechanical or solid state watch in which the time shows through changes of digits, rather than positions of hands on the dial.

Directional compass
Can be displayed by rotating a bezel or digital readout on the face of the watch. It is used to determine a geographical direction using the location of the sun.

Display
Indication of time or other data, either by means of hands moving over a dial (analogue 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 mechanicalor electronic means.

Diving watch: A watch that is water resistant to 200M. Has a one way rotating bezel and a screw-on crown and back. Has a metal or rubber strap (not leather). Has a sapphire crystal and possibly, a wet-suit extension.

Dual Time : A watch that simultaneously display current local time as well as one other time zone. The additional time element may come from a twin dial, extra hand, subdials, or other means

E

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.

escapement: Device in a mechanical movement that controls the rotation of the wheels and thus the motion of the hands. Set of parts (escape wheel, lever, roller) which converts the rotary motion of the train into to-and-fro motion (the balance).
 

F 

Face
The visible side of the watch where the dial is contained, most are printed with Arabic or Roman numerals. Note: traditionally IIII, rather than IV, is used to indicate the 4 o'clock position.

Flyback hand
A seconds hand on a chronograph that is used to determine lap or finishing times for several competitors. To operate, put both the flyback and the regular second hand in motion, then to record a lap or finishing time, the flyback hand can be stopped. After taking the results, push a button and the flyback hand will catch up to the constantly moving second hand.

Frequency
The number of vibrations a second, in hertz (Hz).

G

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.

glass (Crystal): Thin plate of glass or transparent synthetic material, for protecting the dials of watches, clocks, etc.
 

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

H

Hands : The pointing device anchored at the center and circling around the dial indicating hours, minutes, seconds and any other special features of the watch. Watches usually have three hands showing the hours, minutes and seconds.

Hourly time signal
Single beep/chime which rings on the hour, every hour when it is engaged.

I

Index : An hour indicator on an analog watch dial, used instead of numerals.

J

Jewels
Synthetic sapphires or rubies that act as bearings for gears of a mechanical watch. A quality hand wound or automatic mechanical watch contains at least 17 jewels. The jewels reduce friction to make the watch more accurate and longer lasting.

K

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 7-14 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.

L

Lap Memory : The ability, in some quartz sport watches, to preserve in the watch's memory the times of laps in a race that have been determined by the lap timer. The wearer can recall these times on a digital display by pushing a button.

Lap Timer : A chronograph function that 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 the next lap.

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.

Liquid-Crystal Display : (LCD) A digital watch display that shows the time electronically by means of the liquid held in a thin layer between two transparent plates.
 

LumiBrite
environmentally safe illumination technology that will glow brightly for hours without pushing a button or drawing energy from a battery.

Luminous
self illuminating paint used on hands and markers.

M

Manual
A hand-wound mechanical watch.

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
Describes a movement with a balance wheel.

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 body.

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

Military or 24-hour time
When time is measured in 24-hour segments. To convert 12-hour time into 24-hour time, simply add 12 to any p.m. time. To convert 24-hour time into 12-hour time, subtract 12 from any time from 13 to 24.

Mineral glass
Watch glass that has been tempered to increase its scratch resistance.

Moon phase
An indicator that keeps track of the phases of the moon. A regular rotation of the moon is once around the earth every 29 days, 12 hours, and 44 minutes. once set, the moon phase indicator accurately displays the phase of the moon.

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.

Movement
The inner workings or assembly that make up the main timekeeping mechanism. movements are either quartz or mechanical. This is the engine of the watch.

P

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

Power Reserve : The time the watch will run with a fully charged power supply. For mechanical watches it is usually 44 hours. For quartz watches it can vary from 18 moths to 10 years.

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.

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

Q

Quartz crystal movement
A movement which allows a watch to be worn without being wound. This technology employs the vibrations of a tiny crystal to maintain accuracy of time. A digital quartz has no mechanical parts but is powered by a battery.

R

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.
 

S

Sapphire
Transparent sapphire is used for scratch-proof watch glasses.

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 government 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.

Skeleton Hands : Cutout hands showing only the frame.

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

Split time measurement
Measures the elapsed time of a certain moment of an event.
If you want to know the elapsed time at a certain point during a track meet, you can tell exact time by using this.
The chronograph keeps running while split time is being displayed. Therefore, when split time is released the display returns to original measurement of total elapsed time.

Stainless Steel : An extremely durable metal alloy (chromium is a main ingredient) that is virtually immune to rust, discoloration and corrosion; it can be highly polished, thus representing a precious metal. Due to this and the importance of white metal jewelry, steel has become a popular setting for diamonds. Because of its strength, stainless steel is often used even on casebacks of watches made of other metals.

Stopwatch
Timekeeping instrument which can be used for measuring intervals of time. When this is done, the time display is partly or wholly lost until the hands are reset.

Strap
A watch band made of leather, plastic or fabric.

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.

Sweep Seconds-Hand : A seconds-hand that is mounted in the center of the watch dial.

T

Tachymeter (also tachometer)
A watch function that measures the speed at which the wearer traveled by means of a numeric scale on the watch bezel of a chronograph. Frequently used to determine a speed of a car over a measured distance.

Telemeter
A watch function that finds the distance of an object from the wearer by measuring how long it takes sound to travel that distance. Like a tachymeter, a telemeter consists of a stopwatch function and a special scale on the dial of a chronograph.

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 with a silvery-gray appearance. Because it is 30 percent stronger and nearly 50 percent lighter than steel it has been increasingly used in watch making, especially sport watch styles. Its resistance to salt water corrosion makes it particularly useful in diver's watches. Since it can be scratched fairly easily, some manufacturers use a patented-coating to resist scratching.

Two Tone : A watch that combines two metals, usually yellow gold and stainless steel in the case of fine watches.

U

unidirectional rotating bezel: An elapsed time rotating bezel (see "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.
 

W

Water resistant
Water-resistance is usually measured in atmospheres (ATM), which is equal to 10 meters of water pressure. (Some European-made watches use the term "bar" instead). Watches come in different depths of water resistant as below :
Water resistant— Wearable while water is being splashed but not under any pressure
50M Water Resistant —Wearable around sink, during swimming, athletic sport, in shallow water but not while snorkeling or scuba diving.
100M Water Resistant —Wearable around sink, during swimming, poolside diving, snorkeling.
200M Water Resistant — Wearable around sink, during swimming, snorkeling, jet-skiing, but not scuba diving

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).