Accutron: The first electronic watch, controlled by a tuning fork and launched by Bulova in 1960.

Acrylic Crystal: Sometimes referred to as Hesolite or Hesalite, an acrylic crystal is basically plastic. Polymethylacrylate is often used. Benefits of an acrylic crystal are that is flexes rather than shatters on impact, it doesn't produce too much glare under bright light and it can be polished easily.

Agate: A variety of the quartz group that exists in many different colors and is opaque. This ornamental gemstone is sometimes used for watch dials.

Aiguilles: (French) The hands of a clock or watch. The cuvette of a Swiss or French key-wound watch is sometimes stamped AIGUILLES as a warning that the hands are set through the nearby hole rather than by placing the key directly over the exposed end of the cannon pinion in the center of the dial.

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.

Alarum: Horologists seem to prefer this Shakespearean spelling for a clock or watch that sounds an alarm at a pre-set time. Alarum mechanisms are found on some of the earliest mechanical timekeepers and were being fitted to timekeeping devices before 1600.

All-or-nothing piece: A system that prevents an insufficiently wound striking mechanism from striking too few hours.

Alloy: Combination of two or more pure molten metals. Generally, an alloy is given the name of the dominant metal.

Altimeter: A function that provides altitude by responding to changes in barometric pressure, commonly found in pilot watches. Note that inside a pressurized airplane cabin, the altimeter will register as if on land.

American gauge: A system of measuring the sizes of watch movements. Size 0 equals 1.167" or 29.63mm and each step upwards or downwards consists of a step of 0.0333" (0.846mm); size 18, the largest in common use, is 1.688" (45.72mm). Sizes below 0 are expressed (in diminishing order) as 2/0, 3/0 and so on downwards, 1/0 being omitted. The American gauge, like the Lancashire gauge which was its source, measures the diameter of the front plate.

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'.

Analog (also spelled Analogue): Analog 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.

Anchor: The anchor, sometimes referred to as Swiss anchor helps perform the final part of the mechanical process in a mechanical watch in order to divide the seconds and provide accurate timekeeping. Moving side to side, the anchor allows the final wheel (escape wheel) to rotate one cog at a time. This process produces the ticking sound of a mechanical watch.

Ancre: The French term for the lever escapement in its usual 20th-century form, with the arm that carries the pallets mounted at a right angle to the lever itself so as to give a rough likeness to an anchor.

Arbor: The axle or shaft on which a wheel or pinion is mounted.

Arcading: A distinctive treatment of the minute track on some 18th-century watches; between each pair of hour numerals the track is shaped in an ornamental semicircle. This pattern is especially associated with Dutch watches.

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

Atomic time standard: Provided by the U.S. National Institute of Standards and Technology, Time and Frequency Division, Boulder, Colorado, atomic time is measured through vibrations of atoms in a metal isotope that resembles mercury. The result is extremely accurate time that can be measured on instruments. Radio waves transmit this exact time throughout North America and some "atomic" watches can receive them and correct to the exact time.

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: Automatic or automatic watches usually refers to those mechanical watches which wind themselves by means of a swinging mass or rotor (which rotates by arm movement) which through a series of gears, winds the mainspring which in turn powers the watch.

B

Baguette: Ladies style watch with a thin, elongated face; usually rectangular in shape but may be oval.

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 slow the timekeeping.

Bar: 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.

Blued Screws: Screws which were artificially blued, more for decoration than function. The highest grade is furnace blued, which refers to the screws being superheated and dipped in a mineral bath to achieve their blue/black color. The less prestigious way to achieve a similar look is to simply coat the screws with blue pigment.

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 of many movements, and sometimes the cases of inexpensive watches.

Buckle: Mechanical device that closes a strap or bracelet around the wrist. They may be tang, single deployant, or dual deployant in design.

Button: Push piece controls, usually found on the perimeter of a watch case and used to control special functions such as the chronograph or the alarm.

C

Cabochon crown: A rounded semi-precious stone or synthetic material fitted into the watch crown and/or pushers as an ornament. Calendar: A watch complication 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.

Caliber (calibre): The dimensions of the watch or movement. Caliber describes the size and configuration of the movement and can indicate the shape, origin and manufacturer as well.

Cambered: Refers to a curved or arched dial or bezel.

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

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

Chronograph: A stopwatch function built into a wristwatch. Most have two or three sub dials for measuring minutes and hours.

Chronometer: Movements which meet specific timekeeping criteria laid down by the Swiss Official Chronometer Control are awarded a Chronometer Certificate, or COSC. Movements are usually tested out of the case for 15 days and nights in various positions and at various temperatures.

Clasp: The attachment used to connect the two ends of the watch bracelet or strap around the wrist.
• Single Deployant Buckle- A dual-folding enclosure, which secures the two ends of the bracelet and allows enough room for placing the watch on the wrist when fully deployed. When closed, the buckle covers the two-piece folding mechanism.
• Dual Deployant Buckle- Same as above, but with three folds instead of two.
• Fold-Over Buckle—describes either of the above.

Complication: Another function besides time keeping. For example, a chronograph is a watch complication. other complications coveted by watch collectors include: minute repeater, tour billion, perpetual calendar, or split second chronograph.

Corrector: System to set the watch indicators (the hour, minute or day) by means of the crown.

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

Crown: Nodule extending from the case that is used to set the time, date, etc. Most pull out to set the time. In water resistant styles, the crowns may screw down to secure properly.

Crystal: The transparent 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 non-reflective coating on some styles prevents glare.

D

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

Decorated Movement: Some watch movements come highly decorated, for example with Geneva Stripes and blued screws. Whilst decoration may not improve function, it often indicates a degree of hand assembly/finishing and an attention to detail in the construction of a watch. Some watches show off the decorated movement through the use of a display back. Dial: The watch face. The numerals, indices, or surface design are usually applied; others may be molded or printed.

Dial: The dial, often referred to as the face is usually marked with numbers or batons to which the hands point in order for the wearer to tell the correct time. Dials themselves can be very simple, sometimes with no markers at all or extremely complex as in the case of pilots' chronographs. Dials can be crafted from any number of materials (though the most common basis is brass) and decorated with patterns and/or in some cases with precious stones.

Digital: Any watch that shows the time in numbers instead of hands on the dial. The numbers can 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. The time can also be displayed via mechanical wheels showing through one or more windows.

Display: Indication of time or other data, either by means of hands moving over a dial (analog display) or by means of numerals appearing in one or more windows (digital or numerical display). Such displays can be generated by mechanical or electronic means.

Divers Watch: A watch that meets various standards regarding water resistance, pressure resistance, readability in the water, time presetting function (rotating elapsed time bezel), anti-magnetic ability, anti-shock, rust resistance in salt water, manageability in water, ability to withstand sudden temperature changes, etc. The rotating bezel will only rotate counter clockwise. this is so in case rotated accidentally the bezel will not show an extended diving duration. For accurate setting, this bezel also has a one minute interval click. Straps or bracelets feature extra large buckles for easy fastening and longer length to allow it to be worn over a diving suit. The bezel may be set higher than the surface of the crystal to help protect it. Large luminous hands and markers are designed for clear readability.

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