Analog Watch: A watch with a dial, hands, and numbers or markers that present a total display of 12-hour time spans. Analog digital refers to the watch that has both a digital display and hands of a conventional watch.

Automatic Movement: A mechanical movement that requires no winding because the rotor, part of the automatic mechanism, winds the mainspring every time you move your hand.

Bezel: The surface ring on the watch that surrounds and holds the crystal in place. A rotating ratchet bezel can be moved 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 of elapsed time.

Bracelet: A type of watchband made of elements that resemble links. Caliber: A term often used by Swiss watchmakers to denote a particular model type, such as Caliber 48 meaning model 48. More commonly, the term is used to indicate the movement's shape, layout, or size.

Cambered: Often used in referring to a curved or arched dial or bezel. Case: The metal housing of a watch's parts.

Caseback: The reverse side of a watchcase that lies against the skin. May be solid or perhaps transparent to allow viewing of the inner workings of the watch. Most manufacturers engrave casebacks with their name, water and shock resistance, case metal content and other details.

Chronograph: A multifunctional watch with two independent time-keeping systems, which allows one to be stopped to measure discrete intervals, most commonly used as a stopwatch function.

Complication: A watch with other functions besides basic timekeeping, which include chronographs, minute repeater, tourbillion, perpetual calendar, or split second chronograph.

COSC: The official Swiss Chronometer Testing Institute that puts every chronometer watch through a rigorous, 15-day testing procedure to verify the watch's precision.

Crown: The knob extending from the case that is used to set the time, date, and functions. Most pull out to set the time. In water resistant styles, the crowns should screw down to seal the opening.

Crystal: This refers to the clear cover over the watchcase.
Deployment Buckle: A type of buckle that pops open and fastens using hinged extenders. A deployment buckle is easier to put on and remove and is more comfortable on the wrist.

Dial: The watch's face.

Direct-Drive: A function that allows the second-hand to advance in intervals rather than a smooth sweep for more accurate precision, the French term is a trotteuse.

Dual Timer: A watch that measures current local time as well as at least one other time zone.

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

Face: The visible side of a watch where the dial is contained.

Fly-Back Hand: An additional hand on a chronograph which moves with the second hand but, can be stopped independently to measure an interval which can then "fly back" to catch up with the other hand.

Gasket: Most water resistant watches are equipped with gaskets to seal the caseback, crystal, and crown to protect against water infiltration during everyday wear.

Guilloche: A style of intricate engraving that is popular on watch dials.

Horology: The science of time measurement, including the art of designing and constructing timepieces.

Index (indices, pl): Hour indicator on analog watch is used instead of numerals.

Jewels: The synthetic sapphires or rubies that act as bearings for gears of a mechanical watch. These jewels tend to retain the watch's lubrication better and with far less friction than metal. A quality hand-wound or automatic mechanical watch contains at least 17 jewels.

Jump Hour: An indicator on the dial that takes place of the hour hand. It usually shows the hours by means of a numeral in a window.

Lugs: Extensions on either side of the bezel where the bracelet or strap is attached.

Mystery Watch: This is the patented invention of watchmaker Vincent Calabrese and produced by Jean Marcel. The Mystery automatic mechanical watch uses no hands to indicated hours, minutes, or seconds. A jumping hour window moves clockwise around a minute scale while a second indicator, an arrow, also ticks around. Gently breathing on the crystal causes the word "mystery" to appear.

Perpetual Calendar: A calendar complication that adjusts automatically to account for different lengths of the month and leap years.

Pulsimeter: The scale sometimes found on a chronograph that measures pulse rate.

Quartz Movement: A movement that allows a watch to keep time without being wound.

Skeleton Case: If shock resistance is specified on a watchcase, a watch can withstand normal wear and tear, even during strenuous sports activities.

Sweep Second Hand: A second hand mounted in the center of the dials instead of a sub-dial.

Tachymeter (Tachometer): A watch complication that measures the distance traveled by means of a numerical scale on the watch bezel of a chronograph. Most commonly used to determine the speed of a car over a measured distance.

Tank Watch: A rectangular watch with the heavier bars on either side of the dial, inspired by the tank tracks of World War 1 and created by Louis Cartier.

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

Tonneau Watch: A watch with a barrel-shaped case with two convex sides.

Tourbillion: A complicated mechanical movement designed to be more accurate by eliminating errors of motion due to gravity's effect on the movement.

Tritium: An isotope of hydrogen that is used to activate the luminous dots or indices on a watch dial. The radioactivity released in this process is too 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.

Waterproof: An illegal and misused term: no watch is fully 100% waterproof.

Water Resistant: A watch's resistance to water measure in atmospheres, which are translated into ATMs.