Watch Dictionary:

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Watch Terms (A)

alarm - A feature of a watch that produces a sound at a pre-set time.
analog - Time is displayed on a dial with the use of hands to indicate the time.
anodized - A very hard, ceramic coating on aluminum created by an electrolytic process. Various colors may be produced using this coating process.
anti-magnetic - A watch that is resistant to magnetism. A term used to describe the use of non-magnetic materials used in the parts of a watch most affected by magnetization (balance wheel, balance spring and escapement).
antiquarian horologist - A person who practices the art and science of horology, with specific or specialized interest in the study of antique timepieces.
aperture - Small open windows on the dial of a watch used for displaying certain indications, such as day, date, month, hours, minutes, etc.
Arabic numerals - A style of numerals commonly used on watch dials (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12).
arbor - An axis or shaft supporting a moving part such as a wheel or lever.
ATM (atmosphere) - The waterproof pressure ratings of a watch. A watch rated to One Atmosphere would be waterproof to 10 Meters or 30 Feet.
atmosphere (ATM) - The waterproof pressure ratings of a watch. A watch rated to One Atmosphere would be waterproof to 10 Meters or 30 Feet.
automatic mechanical wind - A watch which has mechanical moving parts and winds its mainspring automatically using an internal rotor system.
automatic winding - The watch mainspring is wound automatically by a device inside the movement which rotates due to normal wrist motion while wearing the watch.

Watch Terms (B)

baguette - A diamond or gem cut in the shape of a narrow rectangle.
balance - A series of internal parts known as the balance assembly. Oscillating back and forth governs or controls the watch escapement of power, dividing each swing or oscillation of the balance into two equal parts of time.
balance cock - An internal bridge that supports the balance assembly in position.
balance spring - An internal part of a watch which controls the balance wheel oscillations. Due to its size, it is sometimes referred to as a hairspring.
balance staff - The axle or shaft of the balance wheel.
balance wheel - A component of the balance assembly comprised of the balance wheel, hairspring, balance weights, rollers, roller jewels and staff. This assembly controls or governs the escapement and oscillation or time rate of the movement.
barrel - A cylindrical drum-shaped machine part holding the mainspring that powers the watch.
beat - The sound of a watch "ticking," usually about 1/5 of a second. The escape wheel striking the pallets produces the sound.
bezel - A frame or ring which holds the crystal of a watch.
bracelet - A type of metal attachment designed for securing a watch to the wrist.
Braille watch - A watch designed especially for sight-impaired individuals. There is no crystal over the dial. It is fitted with protrusions in place of normal numerals so the characters and hands may be touched by hand.
bridge - An internal part of the watch movement that has two supports. These help make up the frame of the movement that holds parts together.
bubble back - A slang term given to the first style of automatic winding watch made by the Rolex Watch Co. due to its larger than normal "bowed out" or "bubble style" case back.
buttons - External pieces mounted on the outside edge of a watch case used to activate various functions of a watch, such as the chronograph and alarm features.

Watch Terms (C)

cabochon - A gem that is highly polished, yet uncut.
calibre - The physical size design or layout style of the internal movement of the watch. Many watch companies have numbered these designs for identification purposes.
carillon - A style of repeater watch that strikes on three chime rods (instead of two) which are tuned to octaves.
case - The primary housing for the internal watch movement.
chronograph - A watch with a complicated feature allowing measurement of fractions of a second and elapsed time, independent of the watch displaying normal time.
chronometer - A watch which has been measured for accuracy and tested for precision by an official testing institute.
chronometer escapement - A high-grade escapement invented in the late 1700s for use in larger style mechanisms (marine or box chronometers) on ships to determine longitude. The most famous type of chronometer escapement is the "detent" style.
Civil Day - The accepted ordinary way of keeping time in most parts of the world. The day is divided into two parts, each from 1-12 hours. One part for day, and one part for night. Also known as the Mean Solar Day.
coin watch - A watch in which a coin is used as the case.
complication - A term used to describe an added feature to a watch, making it more than a simple timepiece. Examples: chronograph, split-chronograph, day, date, month, repeater, etc.
Coordinated Universal Time (U.T.C.) - The official measurement of time throughout the world, completely independent of all time zones.
crown - A knob on the outside of the watch case used for winding the mainspring, setting the time and calendar functions.
crystal - The transparent part over the dial used to protect the dial and hands of the watch. Pocket watch crystals were originally made of glass. Wrist watch crystals are normally made of synthetic materials, such as synthetic mineral crystal or acrylic.
cyclops - A slang term for the small lens on the crystal used to magnify the date.

Watch Terms (D)

damaskeen (damascene) - Ornamental engraving on the plates and bridges of a watch. This includes etched designs and geometric patterns.
date - Displayed on a watch dial, the numbers 1-31 represent the days of a calendar month, or the named day of the week and the number of the calendar month. Watches that display perpetual calendar functions will also display the named calendar month and sometimes the leap year cycle (1-4).
demi-hunter case - A style of watch case that has a closed lid or cover over the dial, but a small opening in the center of the lid to read the time without having to open the lid to view the complete dial.
deployant clasp - A hinged fold-over style metal clasp that opens and closes easily, allowing the watch to be placed on the wrist or removed without the use of a traditional buckle.
detent - An internal movement part which locks on part of a mechanism. In the setting mechanism of a watch, a detent could lock into the setting position, winding position and possibly a quickset date position.
dial - The part of a timepiece which allows you to read the time or observe other functions the timepiece may perform. Also known as the face.
digital watch - A watch that displays time directly using Arabic numerals instead of the use of a dial and hands.
display back - The case style of a pocket or wrist watch with a crystal mounted as the case back so the movement may be easily viewed.
double-quick - A setting position from the watch winding stem assembly allowing a person to change the day and date without having to advance the hands through a 24 hour period.
dual-time - A watch that displays the time from two separate time zones. Normally, these watches are made with two separate movements.

Watch Terms (E)

ebauche - A commercial term in the watchmaking industry for an unfinished movement. Some companies specialize in the manufacture of rough finished movements, while other companies specialize in the finishing and assembly of these movements.
electric watch - A timepiece which uses the energy from a battery to run electro-mechanical components as well as wheels, gears and pinions that are common to traditional mechanical watches. Electric watches use analog display and were first marketed in 1957 by the Hamilton Watch Company, USA.
electronic watch - A battery powered watch which uses electrical energy to cause a synthetic quarter crystal to vibrate at the very high rate of 100 kilocycles per second. Electronic quartz watches are some of the most accurate watches produced.
Elinvar - Derived from the words "elasticity" and "invariable," this hairspring is composed of a special alloy which does not vary (expand or contract) with temperature change.
Ephemerous Time - The time calculated for the Earth to orbit once around the Sun.
equation of time - The difference between solar time as displayed on a sun dial and Mean Time. With the use of an Equation of Time table, it is possible to calculate Mean Time with the results of a sun dial and conversion tables.
escape wheel - Escaping one pulse at a time, it is the last wheel in a train, and works with the fork or lever.
escapement - A series of internal parts which allow the release of mainspring power through the rotary motion of the watch train of wheels into the back and forth motion of the balance assembly oscillation into equal time intervals.
exposition back - A case style of a pocket or wrist watch where the crystal is mounted as the case back so the movement may be viewed easily.

Watch Terms (F)

five-minute repeater - A complicated watch that strikes (chimes) the hours and five-minute intervals.
fly-back hand - A feature of a watch which allows you to measure fractions of a second and elapsed time by two separate recording hands, independently of the watch displaying normal time.
fob - A small, decorative object that is attached to a pocket watch chain and worn outside the pocket or vest for viewing. Objects such as lodge and commercial company logos were very popular, as well as miniature objects like trains and horses.

Watch Terms (G)

GMT - Greenwich Mean Time is the standard for timekeeping and was introduced in England in 1880. It is the Mean Time of a Solar Day.
gold-filled - A thin sheet of gold (normally at least 20 microns thick) which is bonded to one or both sides of a base metal.
gold-plated - A coating of a gold alloy over a base metal by either electro-depositing and/or a chemical process. Recommended minimum thickness should be 10 microns thick.
Greenwich Mean Time - Greenwich Mean Time (GMT) is the standard for timekeeping introduced in England in 1880. It is the mean time of a solar day.
guilloche - A pattern or style of pattern on a case or dial known as "engine-turned."

Watch Terms (H)

hack movement - A style of movement normally fitted with a sweep center seconds hand, where the balance assembly is stopped when the watch is placed in the setting position. This allows the time to be set more accurately.
hairspring - An internal part of a watch which helps control the balance wheel's oscillations. Sometimes referred to as the balance spring.
half-quarter hour repeater - A complicated watch that strikes (chimes) the hours and nearest half-quarter hour.
hand - An indicator mounted over a dial or scale to indicate the time or other functions of a watch. It is normally made of metal in many styles and designs.
horologist - A person who practices the art and science of horology.
horology - The scientific and artistic study of the working of mechanisms designed to indicate the time of day and the measurement of the passage of time.
hunting case - A style of case that has a closed lid or cover over the dial which can be opened and closed by a spring-release button. Both pocket and wrist watches use this style of case design.

Watch Terms (I)

Incabloc - A type of shock-resisting system where the jewels have springs to hold them in place. This allows the balance to have some 'give' if the watch receives a shock.

Watch Terms (J)

jewel - The internal part of a watch used to reduce friction, such as a bearing. Normally made of synthetic material. However, some high grade watches use both precious and semi-precious stones.
jumping hour - A watch with apertures on a solid case front with small dials behind the apertures displaying one hour indications at a time. Normally, minutes are displayed in a semi-circular aperture which displays more than one minute indications on a circular dial.

Watch Terms (K)

karat - Standard by which the fineness or purity of gold is defined. 24 karat fine is pure gold (1000/1000 parts). 18 karat is 75% pure gold (750/1000 parts). 14 karat is 56% pure gold (560/1000 parts).
karruesel - Self-compensating device designed to overcome various vertical position timing errors. The entire escapement and balance assembly is mounted on a carriage and revolves like a tourbillon, only more slowly.
key-set - Method of setting the hands of a keywind/keyset pocket watch by using a small key. The key is placed on the setting arbor and turned to set the hands.
key-wind - Refers to winding an antique watch with the use of a key and winding arbor on the movement.

Watch Terms (L)

L.E.D. - (Liquid Electronic Display). A semi-conductor diode which transforms applied voltage and converts it into light. LED is used in digital displays on electronic quartz watches.
Leap Year - One extra day (February 29) is added to the calendar every four years to compensate for the quarter-day difference in an ordinary year (Mean Solar Year) and the astronomical year (Sidereal Year).
lever set - Method of setting the hands on a pocket watch by using a lever located under the bezel. The lever is pulled to the "out" position, then the winding crown is turned to set the hands.
Liquid Electronic Display - (LED) A semi-conductor diode which transforms applied voltage and converts it into light. LED is used in digital displays on electronic quartz watches.
lugs - Two pairs of case extensions at opposite ends of the case which allow attachment of the band or bracelet to the watch case.

Watch Terms (M)

mainspring - The principal or power spring of a watch.
mainspring barrel - A geared barrel that houses the watch mainspring.
marine chronometer - A high-grade, larger mechanism invented in the late 1700s for use on ships to determine their longitude. Mechanical chronometers are placed in wooden boxes and mounted on gimbals so they will constantly remain in the horizontal position for greater accuracy.
Mean Solar Day - The average of all of the solar days in one year.
mechanical automatic wind - A watch which has mechanical moving parts and winds its mainspring automatically using an internal rotor system.
mechanical manual wind - A watch which has mechanical moving parts and requires its mainspring to be manually wound.
minute repeater - A complicated watch that strikes (chimes) the hours, quarter hours and minutes past the previous quarter-hour.
moonphase - The function or complication of a watch which displays the phases of the earth's moon cycle.
movement - The internal mechanism of a watch. Assembly of parts and main components such as the mainspring, balance assembly, escapement, train of wheels, setting and winding .
musical watch - A watch made with a mechanism like a music box that plays a melody on each hour automatically, or on demand with a slide or button.

Watch Terms (O)

offset seconds - A style of dial where the sub-seconds of a watch is located to one side of the conventional 6:00 location of a sub-seconds dial.
open face - A style of case where the dial is open to view and is not covered by a lid or cover, as in a hunting style case.
Oyster Perpetual - A term given by Rolex to the movement of it's self-winding waterproof watches
Oyster watch - The name given by Rolex Watch Company to their waterproof watches.

Watch Terms (P)

pallet - Shaped like a ship's anchor, this is part of the lever escapement.
patina - Discoloration or oxidation of any surface due to age.
pave - A style of setting stones so close together that no metal is allowed to show.
pendant - The part of a pocket watch where the bow and winding crown are attached.
pendant set - Method of setting the hands on a pocket watch by using the stem and winding crown.
perpetual calendar - A function or complication of a watch which displays correctly, without adjustment, the day, date and month, and also accounts for leap year cycles.
pivot - The end of an arbor which has been reduced or turned down. Three common styles of pivots are conical, cone and square shoulder.
plate - This part of the movement supports the other plates and bridges.
platinum - A hard, white metallic element used in the manufacture of watch cases and bracelets.
pocket chronometer - A pocket watch fitted with a chronometer-type escapement.
pocket watch - A watch designed to be worn in a pocket.
power reserve indicator - An indicator hand on a dial which displays how much the mainspring is wound up or down.
pulsimeter - Type of chronograph with a dial scale indicating the average heartbeat rate over a certain period of time.
push button - External button on outside edge of case. Used to start or stop specific functions or complications of the watch, such as chronographs and alarms.
pushers - External pieces mounted on the outside edge of a case used to activate various functions of a watch, such as the chronograph and alarm features.

Watch Terms (Q)

quarter-hour repeater - A complicated watch that strikes (chimes) the hours and quarter-hours.
quartz watch - A watch whose battery-powered mechanism uses electrical energy to cause vibrations in a synthetic quartz crystal at the very high rate of 100 kilocycles per second. Electronic quartz watches are some of the most accurate watches produced.
quick-date - A setting position from the watch winding stem assembly allowing a person to change the date without having to advance the hands through a 24 hour period.
quick-set - A setting position from the watch winding stem assembly allowing a person to change the day or date without having to advance the hands through a 24 hour period.

Watch Terms (R)

regulator - Part of the watch movement used to speed up or slow down the beats, bringing the watch to more exact timing.
repeater - A function or complication of a watch which strikes (chimes) the hours by an internal mechanism operated by an external lever or button. Various types of repeater designs have been made. A minute repeater strikes the hours, quarter hour and minutes past the previous quarter hour. A quarter-hour repeater strikes the hours and quarter hour. A half-quarter-hour repeater strikes the hours and nearest half quarter hours. A five-minute repeater strikes the hours and five minute intervals past the hour.
reverso - A style of rectangular wrist watch case that can be turned over or reversed within the main frame of the case. One side shows the view of the normal dial, and one side either has the back of the case or another dial type, such as one for displaying dual-time.
rhodium - A hard, white, metallic element that is of the platinum element group. Often used to alloy with platinum. Often used in the manufacture of watch cases and bracelets.
rolled gold plate - A thin sheet of gold (normally at least 20 microns thick) which is bonded to one or both sides of a base metal.
Roman numerals - Style of numerals commonly used on watch dials (I, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII).
rotating bezel - Style of bezel which rotates to measure elapsed time, dual time and mathematical functions. These style bezels are normally designed for and used on aviation and scuba diving watches.
rotor - Half round shaped weight which rotates inside a mechanical automatic winding watch and winds the mainspring when the watch is worn. Rotors are normally made of non-precious metals. However, some high grade watches use precious metals like gold and platinum.
round - Style of watch case that is circular.

Watch Terms (S)

sapphire crystal - Synthetic watch crystal that is extremely hard and very scratch resistant.
self-winding - The watch mainspring is wound automatically by a device inside the watch which rotates during normal wrist motion when the watch is worn.
setting - Procedure of rotating the winding and setting crown to bring the hands of a watch to the position of correct time.
shock resistant - A watch movement in which the balance staff end stone jewels are sprung so that when the watch is subjected to a shock, there will be some 'give.'
Sidereal Day - Actual time the earth takes to rotate once a day with the use of a fixed star as a reference point. The measurement interval of time is taken between two successive transits of the same star over the same meridian. A Sidereal Day is 3 hours and 56 seconds longer than the mean time of a solar day.
Sidereal Time - Primarily used in observatories for the study of astronomy. It is the time measured between two consecutive meridian transits of a fixed star.
skeleton - A mechanical watch movement that has had as much material cut away from the plates and dial as possible during the manufacturing process to render the greatest view possible of the watch wheels and escapement. It is normally cased in a watch case where the crystal is mounted on both the front and back to create a very decorative watch.
Solar Day - The actual time the earth takes to rotate once a day with the use of the sun as a fixed point of reference. The measurement interval of time is taken between two successive transits of the sun over the same meridian.
Solar Time - The time of day determined by the sun. Example: the use of a sun dial to measure solar time.
split-second chronograph - The feature or complication of a watch which allows you to measure fractions of a second and elapsed time by two separate recording hands, independently of the watch displaying normal time.
spring bar -
square - Style of watch case in which each of the four sides are equal size.
stem - The winding shaft that connects into the movement's winding and setting mechanism. The winding crown is fitted to the opposite end of this shaft.
stem wind - Refers to the winding of a manual wind mechanical watch with the use of a winding crown and stem attachment to the movement.
stop watch - A timekeeping instrument used for the measurement of time intervals in fractions of a second, such as those used at sporting events.
strap - A piece of leather or synthetic material used for securing a watch to the wrist.
sub-dial - A smaller dial on the main dial of a watch displaying a feature of the watch. Example: constant second hand, minute and hour counters, days, dates, months, leap years, etc.
sub-seconds hand - A smaller sub-dial on the main dial displaying constant seconds.
sweep seconds hand - A seconds hand mounted in the center of the dial displaying constant seconds.

Watch Terms (T)

tachometer - Watch or stop watch used for the measurement of speed. Normally a timer or chronograph with a graduated dial or bezel allowing the speed of a vehicle to be figured in miles per hour or kilometers per hour.
tantalum - An extremely hard, metallic element which is gray in color and highly resistant to corrosion. Used in the manufacture of watch cases and bracelets.
telemeter - A watch or stop watch used for the measurement of the distance an object travels over a period of time. It is normally a timer or chronograph with a graduated dial or bezel, allowing the speed of an object to be computed in kilometers or miles per hour wi
Time - Units of measurement of the rotation of the earth on its axis.
time zone - A portion of the earth's surface where the same time is agreed upon.
timepiece - A watch or clock which displays only the time of day.
timer - A timekeeping instrument used for the measurement of time intervals in fractions of seconds, such as those used at sporting events.
titanium - A strong, lightweight metallic element, gray in color, which is highly resistant to corrosion. It is used in the manufacture of watch cases and bracelets.
tonneau - Style of a rectangular or square wrist watch case that is wider (bowed outward) on the sides of the case in the center and tapers toward both ends.
tourbillon - Self-compensating device designed to overcome various vertical position timing errors. The entire escapement and balance assembly is fitted into a cage, and the complete assembly rotates every 60 seconds.
train - The series of wheels and pinions in a watch or clock comprised of the Center Wheel, Third Wheel, Fourth Wheel and Escape Wheel. The mainspring band and balance assembly are not considered part of the train.
triple calendar - A complicated watch movement with a dial which displays the day, date and month.
tritium - A substance applied to hands and hour markers to make them luminous so they will glow in the dark.

Watch Terms (U)

U.T.C. - (Coordinated Universal Time) - The official measurement of time throughout the world, completely independent of all time zones.
up and down indicator - A smaller sub-dial on a watch dial or a separate indicator which displays how much the mainspring is wound up or down. Normally, the dial or indicators read "up and down." 'Down' is the zero wound position. 'Up' is maximum wound position.

Watch Terms (W)

watch case - asymmetrical - A style of watch case that is irregular in shape.
watch case - coin - A watch case in which a coin is used as the case.
watch case - cushion - A style of square wrist watch that is wider (bowed outward) in the center of all four sides of the case.
watch case - round - A style of case that is circular.
watch case - square - A style of watch case in which each of the four sides are equal size.
watch case - tank - A style of rectangular wrist watch case design.
watch case - tonneau - A style of a rectangular or square wrist watch case that is wider (bowed outward) on the sides of the case in the center and tapers toward both ends.
water proof - A design feature of a watch case made to withstand complete submerging. Some waterproof watches are also designed to withstand extreme water pressures, as needed in watches used for scuba diving.
water resistant - A watch designed to withstand rain and splashes of water, but not designed to withstand submerging.
white gold - Yellow gold that is alloyed with palladium.
winding - Procedure to wind a watch mainspring. This can be done by rotating the winding crown on a manual wind watch or automatically by wearing a watch with a rotor winding system in an automatic winding watch.
winding crown - A knob located on the outside of the watch case used for winding the mainspring and setting the time and calendar functions.
World Time Watch - A type of watch which gives the time in different cities in the world by way of a moveable dial.
wrist watch - A watch designed to be worn on the wrist and held on by a strap band or bracelet.

Watch Terms (Y)

Yacht-Timer - Style of watch used to count down a boat race.