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Watch Glossary

12-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.
30-minute recorder (or register)
A sub-dial on a chronograph (see "chronograph") that can time periods of up to 30 minutes.
A group of chemical compounds containing the acryl group which is derived from acrylic acid, methacrylic acid or related compounds. In watches acrylic resins, which are thermoplastic or themosetting plastic substances (hard "plastics"), may be used for crystals and case material.
The watch alerts you with beeps at pre-set time(s).
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).
A watch that shows the time using hour and minute hands.
A treatment to the watch glass which assures the dispersion of reflected light.
Arabic numbers
The ten numerical symbols; 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.
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.
A timepiece with figures or other devices that move.
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.
The ring that surrounds the watch dial (or face) and secures the crystal. The bezel is usually made of metal and/or plastic and may be independent of - or contiguous with, the case. The bezel may be fixed or moveable. Moveable bezels are often used to make mathematical calculations.
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"). Many chronographs, special use and high tech watches have calculating bezels.
A purposeful uniform "scuffing" of metal producing a finish that is clean and uniform. Brushed surfaces "hide" the scratches of everyday wear that may make a "polished" surface look worn. (see "polished")
Built-in illumination
Lighting on a watch dial that allows the wearer to read the time in the dark. Check out Seiko's LumiBrite technology.
A precious stone of convex hemispherical or oval form usually polished but not cut into facets. These stones may be set into the crown, bezel, or strap of watches.
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.
The container which houses and protects a watch's mechanisms. It consists of the bezel, middle, and back.
The plate on the back of the watch by which you can access the watch mechanism and/or battery. Most casebacks are stainless steel, but some are hard plastic. They may be secured by friction, tiny screws, or machined to screw into the case. Inexpensive watches may have a non-removable caseback.
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/or 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") 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.
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.
A jagged or coin-like edge usually seen on bezels.
Additional functions beyond time-keeping such as: autowinding, date, moon-phase, heart monitoring, tide levels, power reserve, full calendar, split-second, perpetual calendar, duel time, world time, etc. These functions often involve precise strings of button sequencing and thick "How-to-Use" manuals "complicating" the knowledge necessary to get the most out of the watch. Watches with the most complications can be found in's "High Tech" and "Special Use" categories.
Usually a subdial on a chronograph which indicates time elapsed in seconds, minutes, or hours and is reset using a sequence and/or combination of presses on the crown and additional chronograph buttons.
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.
Also called a "stem" or "pin", a crown is the small knob on the outside of the watch case with a pin that links to the watch mechanism inside the case. It is traditionally located at three o'clock position but may be at top (many pocket watches), at left (diving watches) or some other location to meet designer's whim. It 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.
The transparent cover on a watch face made of plastic, (easy to scratch, hard to shatter), glass ( harder to scratch, easier to shatter), and synthetic or natural sapphire (hardest to scratch, easiest to shatter). Watch "glass" is similar to window glass and is sometimes called "mineral" glass. Seiko makes a crystal called "Sapphlex" which is a combination of "mineral" glass fused with a thin synthetic sapphire layer which is both scratch and shatter resistant.
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.
The "dial" is the "watch face." The part of the watch that indicates time either with hands (analog) and markers or with lit numbers (digital). The main dial is housed under the crystal. It may be simple or ornate and designs vary in shape and form but all reflect the actual mechanism that underlies it. Watches may have multiple dials and or "subdials" within the main dial indicating fractions of time or functions other than time.
A watch that displays the time by lighting up numerals or digits rather than using rotating hands (analog).
Diving watch
A watch that is water resistant to 200 meters or more. Diving watches may have a one-way rotating bezel for diving calculations and a screw-down crown and caseback for enhanced water resistance. Diving watches usually use a metal or rubber strap (not leather). Many diving watches use sapphire crystals. Some diving watches come with a strap extension allowing it to be worn over wet suit.
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.
Usually a glassy substance applied by fusion to the surface of metal as an ornament or a type of varnish.
Device in a mechanical movement that controls the rotation of the wheels and thus the motion of the hands. (Types include: lever, verge, cylinder, pin-pallet, detent and duplex, and coaxial.)
Face height
A measurement taken in centimeters of the crystal height within the outer bezel. The measurement is usually taken vertically through the center of the watch on a line perpendicular to the width of the wrist. (Note: in asymmetrical watch faces the measurement might be diagonal on the face.)
The engraving on a dial or case covered in enamel.
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.
Having the color of gold but not actually made of gold. (see "Silver-toned")
Covered thinly with gold or gold in color.
An abbreviation for "Greenwich Mean Time"
Energy that is in motion. Refers to watches that are charged through the motion of the wearer. Seiko produces a patented line of "Kinetic®" watches. Their 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, men's 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. For more information, visit Seiko's website. (See also "Automatic winding" which refers to mechanical movement rather than electric.)
Integrated bracelet
A watch bracelet that is incorporated into the design of the case.
Ion-plated. Ionic plating, see 'PVD'.
Real or synthetic precious stones, (traditionally 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 hour
Digital display that changes rapidly at the end of each hour.
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. Used in electronic equipment which uses semiconductor diodes to emit light when conducting currents. Usually displays readings on digital watches.
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.
Projections on a watch case to which the watch band or bracelet is attached, usually with removable spring bars.
Originally radioactive tritium, now non-radioactive materials which emit luminous energy that illuminates hands and markers for easier reading in low light.
Reference points for hands; usually indicating hours, five or fifteen minute intervals.
Rough chiseled look of metal, usually used as a type of detailing on a bracelet or case.
Maximum wrist circumference
A measurement of the maximum wrist size the watch will accommodate. Watch is closed or secured into last buckle hole, secure velcro position, or clasp position and the inside circumference of band plus case is measured in centimeters. (Note: some link bands can be increased with extra links.)
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 kilograms.
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. Mechanical movements may be manual, automatic, or with a variety of winding devices.
A watch which shows moon-phases usually through an aperture (window) on the watch face.
The inner mechanism of a watch that keeps time and moves the watch's hands, calendar, etc. Movements are either mechanical or quartz.
Organic light-emitting diode. Any LED whose emissive electroluminescent layer is composed of a film of organic compounds. Usually polymer substances which allows organic compounds to be deposited.
Pierced with a hole or holes.
Perpetual Calendar
A calendar on a watch that shows month and years without manual adjustments.
Process of adhering one type of metal, usually precious (like gold, silver, chromium, radium or palladium) to brass or steel.
A finish given to the metal on a watch giving it a shiny, clean and uniform look. Polished surfaces may scratch easily in everyday wear (see also "brushed").
A synthetic thermoplastic resin material often used for cases contiguous straps.
A material made out of various resins widely varying in flexibility often used for sport watch straps instead of metal or leather.
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.
Chronograph specifically designed for taking heart rate; after initiation, timer stops after a specific number of beats (15, 20 or 30) depending on its calibration.
Push button, Pushpiece, or Pusher
Mechanical element outside case extending to internal mechanism to control specific functions. Although usually separate from the crown, some crowns behave as pushpins in certain positions.
Physical Vapor Deposition. Vacuum coating techniques used to deposit thin film coatings which enhance the properties and performance of a timepiece's case and bracelet. (I.e. superior hardness and water resistance.)
Quartz movement
A movement powered by an electric current. 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.
A split-second function where the hand has a flyback mechanism.
A watch whose hands move on an arc scale usually 90 or 180 degrees to start new measurement, and are mostly used to indicate date, days, or months.
Roman numerals
Any of the Roman letters that form numerical symbols: I (=1), V (=5), X ( =10), L (=50), C (=100), D (=500), and M (=1,000). The following are those most commonly seen on watches: III (=3), VI (=6), IX (=9), XII (=12)
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.")
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.
Sapphire crystal
A crystal made by heating aluminum oxide to very high temperatures, synthetic sapphire, is one of the hardest compounds. This makes for very scratch-resistant watch covers. It is however brittle and shatters more easily than plastic (see "crystal").
Screw-down crown
A crown that can be screwed into the case to make the watch watertight.
Screw-in caseback
A caseback that requires a special tool to "unscrew" the caseback. This ensures a higher level of water resistance. You can tell if you have a screw-in caseback by the "notches", usually 5 or 6, around the circumference of the caseback.
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 two timezones simultaneously and is sometimes called a "duel-time". carries some watches that are multi-time allowing the user to keep track of more than two times at once.
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.
Shock proof
A watch outfitted with shock absorber mechanisms called "incabloc".
Having the color of silver but not actually made of silver. (see "gold-toned")
Skeleton watch
A watch where parts of the mechanisms are visible through "cutouts" in the dial, often they can be seen through both sides of the case.
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 fuel consumption by an airplane or fuel weight.
Small second
A second hand display that is on a small subdial rather than attached at the same site, usually central, as the hour and minute hands.
Solar powered
A watch that uses light energy (from any source; sun, incandescent, etc.) to power the quartz movement or other functions. A large selection of watches utilizing solar power can be found at (use search engine). Baby G, Casio, Citizen "Eco-Drive®", G Shock, Pathfinder, Seiko, and Swiss Army each offer many models using this technology.
Stepping motor
The part of a quartz movement that moves the gear train, which in turn moves the watch's hands.
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.
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
A high quality watch, where at least 50 per cent of the watch has been made in Switzerland.
("tack IM eh ter") 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.
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 because it does not contain nickel. Titanium is very resistant to corrosion, salt water, and extreeme temperatures. Seiko enhances the scratch resistance of their titanium watches by applying a special glass coating to the metal.
Tonneau watch
A watch shaped like a barrel, with two convex sides.
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.
Watch depth
A measurement in centimeters of the thickness of the watch from front (crystal side) to back (case side) taken at the widest point (usually through the center of the crystal).
Watch width
A measurement in centimeters of the watch including any extensions, decorations, or buttons. In most circumstances this will be the case plus the crown. Includes band if integral to watch. Thus retro watches with wide cuff bands may show watch widths wider than the case. Could be thought of as the narrowest opening a particular watch could pass through if held vertically and passed through straight-on without tilting.
Water resistance
The ability to withstand exposure to water. Please note: "water resistant" does not mean "waterproof". uses the following designations: Watches designated "Water Resistant" to 30 meters (100 feet, 3 atmospheres or ATM, 3 BAR) should withstand accidental splashes; those designated to 50 meters (165 feet, 5 ATM, 5 BAR) should withstand showering or swimming; those designated to 100 meters (330 feet, 10 ATM, 10 BAR) can be used for swimming or snorkelling; those designated to 150 meters (500ft, 15 ATM, 15 BAR) can be used for recreational scuba diving; those designated to 200 meters (660 feet, 20 ATM, 20 BAR) or greater are considered professional deep sea diving watches. Please Note: the water resistance of a watch declines with age; number of times backs have been removed and batteries changed, etc. Diving watches must have their crowns and backs screwed completely down and seals checked periodically for wear to maintain their original water resistant designations.
Winding stem
A small knob used to wind the mainspring in manual-winding watches. Sometimes called the "crown."
Opening in face which reveals underlying numerals indicating date, second time zone, jumping hour, moon-phase, etc.
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."
Small subdial or indicator on main dial used to display various functions.