Alarm - a function designed to alert the wearer at specified time.

Analog display - a term coined to distinguish classic watches from newer digital watches. On analog watch, the time is not displayed as a series of digits, but in a classic manner, typically by the continuous motion of hands, pointing to numbers or indices arranged on a dial. The hour hand's movement is here analogous to the path of the Sun across the sky.

Automatic winding - a function of a mechanical watch in which the mainspring is wound as a result of the motion of the wearer’s body. This kinetic energy causes the rotor to pivot on its staff which, through a series of reverser and reducing gears, winds the mainspring.

Balance - or balance wheel, is a weighted wheel that rotates back and forth. Each swing of the wheel, divides time into equal parts, allowing the gear train to advance a set amount, moving the hands forward.

Balance spring - or hairspring, is a spring attached to the balance wheel. Its purpose is to cause the balance wheel to oscillate with a resonant frequency, forces it back to its neutral position, and thereby adjusts the rate of the timepiece.

BaselWorld - is the leading event for the watch and jeweler industry. The full name of the event is Baselworld – The Watch and Jewelry Show, and it is organized each spring in the city of Basel, Switzerland.

Bezel - is a ring holding a watch face and the protective crystal in position.

Calendar - is an astronomical complication that can display, date, week of year and/or month either alone or in combination. There are many different types of calendars, including simple ones, annual calendars, and perpetual calendars.

Caliber - is a specific watch-movement model, typically denoted by a series of letters and numbers. The mechanism of a clock or a watch.

Case - is the housing that protects the watch movement and gives the watch its distinctive appearance.

Case-back - the reverse side of the case that touches the skin. Some case-backs feature a sapphire-crystal that allows the wearer to admire the movement. Others are solid, and often engraved with commemorative inscriptions, and other important information.

Chronograph - is a type of watch designed for recording time with great accuracy. A basic chronograph timepiece is used as a stopwatch combined with a display watch. It typically features an independent sweep seconds hand that can be started, stopped, and returned to zero to measure short intervals of time. Chronographs that are more complicated use additional complications to measure seconds, minutes, hours and even tenths of a second. On most of them, there is a tachymeter scale for measuring speed and distance.

Chronometer - is a specific type of watch tested and certified by the Contrôle Officiel Suisse des Chronomètres (COSC) to meet the highest standards of precision.

Côtes de Genève - is a watchmaking finish, a pattern of stripes produced abrasively using small disks, polishing wheels or ivory laps.

Crown - is a button or a small crowned pin on the side of the case that is typically used to wind the watch, to stop the watch, or to make certain adjustments such as setting the time, date, and day.

Cyclop’s eye - is a magnifying glass, a piece of sapphire crystal positioned above the date aperture so that it magnifies the numerals for easier reading. Named after a primordial race of giants from Greek mythology who had a single eye in the center of their forehead.

Deployant buckle - is an expanding buckle attached to the strap to that allows the strap to be widened for putting on/off without unbuckling.

Dial - is a face of an analog clock or a watch that displays the time using numbers, indices, and moving hands.

Digital display - indicates the time digitally, as opposed to an analog display, which indicates the time by the positions of hands. On digital displays, the time is displayed as a series of numbers and other symbols.

Ébauche - an incomplete or unassembled watch movement and its components.

Escapement - a device in mechanical watches that conveys energy to the timekeeping element (a pendulum or balance wheel). Each swing of the timekeeping element releases a tooth of the escapement's escape wheel gear and moves the clock's hands forward at a steady rate.

ETA - or ETA SA is the Swiss watch manufacturer of quartz watches and both hand-wound and automatic-winding mechanical ébauches and movements.

Flyback chronograph - a complication that allows the wearer to use the reset function without the need to first stop the chronograph. Also known as retour-en-vol, Taylor system, and permanent zero setting.

Gear train - a system made by mounting gears on a frame, so the teeth of the gears engage without slipping to transmit power from the mainspring to the escapement.

Geneva Stripes - see Côtes de Genève.

Grand Sonnerie - a French word for “grand strike,” is a complication that, on every quarter-hour, strikes the number of quarter hours audibly on a gong, and then the number of hours since the last hour on a second gong.

Grande complication - a watch incorporating several different complications, pushing the boundaries of possibility in mechanical watchmaking. The Vacheron Constantin Reference 57260, with its 57 complications, is widely regarded as the most complicated watch in the world.

Guilloché - a decorative pattern engraved on the dial, case, or movement components, via engine turning. The pattern looks like repetitive design of intersecting or overlapping spirals or other shapes.

Helium escape valve - also known as helium release valve, is found on professional divers watches aimed at operating at great depths for prolonged periods, or under saturation. In such conditions, helium atoms, the smallest natural gas particles found in nature, can find their way into the case and below the crystal. During resurfacing, a pressure difference builds up between the trapped gases and the environment, which may cause a damage to the watch. Helium escape valve releases the helium, hydrogen and/or other gases to equalize the pressure and prevent any possible damage.

Horology - the study and measurement of time. Latin horologium from Greek ὡρολόγιον.

Jewels - or ruby jewel bearings, are small, synthetic stones used in watch movements as bearings for a balance wheel. Their low and predictable friction improves watch accuracy and improves bearing life. The jewel material is usually synthetic sapphire or ruby (corundum).

Lugs - lugs are the parts of the case to which a strap or bracelet is attached. Another name for lugs is horns.

Luxois - Independent online magazine dedicated to luxury timepiece of exceptional quality.

Mainspring - a spiral torsion spring of metal ribbon used as a power source in mechanical watches. Winding the movement stores energy in the mainspring by twisting the spiral tighter. The force in the mainspring turns the clock’s gears as it unwinds, and therefore powers the watch.

Mechanical movement - a moving mechanism used to measure the passage of time. A mainspring drives this type of movement.

Military time - is the timekeeping convention in which the day is divided into 24 hours. Military time is also known as the 24-hour clock.

Mineral crystal - mineral glass crystal is often found in mid-range watches, and it refers to a regular glass crystal that has been heat or chemically treated to better withstand scratches. Mineral glass is more resistant than Plexiglas, or plastic, but still prone to scratching, cracking, or shattering.

Movement - movement is the working mechanism (clockwork) of a watch. A movement is also known as a caliber.

Perlage - a decorative pattern that consists of small, overlapping circles.

Perpetual calendar - a watch complication programmed to perform a calendar function valid for many years. It tracks the date, day of the week, month, year, and a leap year. The perpetual calendar needs to be adjusted once a century.

Power reserve - power reserve indicator is a watch complication designed to show the amount of remaining stored energy. Another name for this complication is Réserve de Marche.

PVD - physical vapor deposition, or PVD, produces thin coating on the surface of the watch.

Quartz movement - a type of movement that uses an electronic oscillator that is regulated by a small piece of vibrating mineral, quartz crystal, to keep time. Quartz watch is powered by the battery that translates those vibrations into time.

Rattrapante - or double chronograph, is a watch that includes two stopwatch mechanisms. This kind of watches is used for measuring two separate events of different durations.

Regulator - regulator watch is a type of watch with hours, minutes, and seconds shown on separate dials.

Repeater - a complication in a mechanical watch that audibly chimes the hours, or even minutes, at a press of a button.

Retrograde hand - a type of hand that travels along a track and, when it gets to the end, it instantaneously jumps back to the beginning.

Rider tabs - parts of the bezel that serve as visual markers, grip aids that facilitate operation while wearing gloves, and protect the crystal covering the dial.

Rotor - a part of the mechanical movement, an eccentric weight that swings back and forth, caused by the wearer's motion, thus winding the mainspring.

Sapphire crystal - the priciest glass crystal material and the most scratch resistant one. In watchmaking we use a synthetically produced crystal, which is second only to diamond in its hardness. Sapphire scores 9 out of 10 on the Mohs mineral hardness scale.

Shock absorber - a system that protects the balance wheel's delicate pivots from damage in the event of physical shock.

SIHH - Salon International de la Haute Horlogerie Genève, held every January in Geneva, is the world’s most important watchmaking event.

Skeletonizing - a technique employed on the watch dial or the movement, to reduce it to the bare essentials, revealing as much of the caliber as it is possible without compromising performance of the watch.

Slide rule - introduced by Breitling, is an integrated circular slide rule specialized for flight calculations including metric to standard conversions, airspeed, rate/time of climb/descent, flight time, distance, and fuel consumption functions, as well as kilometer—nautical mile and gallon—liter fuel amount conversion functions.

Small-seconds - a seconds indication positioned on a separate sub-dial.

Sonnerie - Grand Sonneire a complication in a mechanical watch that combines a quarter striking mechanism with a repeater. Petite Sonnerie only strikes the hours on the hour and the quarter hours on the quarter, with no repeater function.

Split-seconds chronograph - see Rattrapante.

Sub-dial - a subsidiary dial, a small dial located inside the main dial.

Sweeping seconds - the central seconds hand. In quartz watches, the seconds hand jumps in one second increments, whereas in a mechanical watch, the seconds hand sweeps smoothly across the dial.

Swiss Made - a label used to indicate that a product is entirely made in Switzerland. A watch is considered Swiss only if its movement is Swiss, its movement is cased up in Switzerland, and its final inspection was carried out in Switzerland.

Tachymeter - a scale that is sometimes present around the rim of an analog watch, which can be used to calculate a speed based on travel time or measure distance based on speed.

Tonneau - a shape of a watch case resembling a barrel.

Tourbillon - an addition to the watch escapement that cancels out the effects of gravity when the escapement is stuck in a certain position. Tourbillon constantly rotates the entire balance wheel and averages out positional errors, thus improving accuracy of the mechanism.

Water Resistance - a mark on the watch indicating its ability to withstand exposure to water. Watches that are water Resistant 3 atm or 30 m are only splash and rain resistant. Those water resistant to 5 atm or 50 m are suitable for surface swimming, white water rafting, and fishing. Watches water resistant to 10 atm or 100 m are suitable for recreational surfing, swimming, snorkeling, sailing and water sports, but NOT suitable for diving. Water resistance of 20 atm or 200 m makes the watch suitable for skin diving. Diver’s 100m rating indicates that the watch is ready for scuba diving at depths but NOT suitable for saturation diving, Diver’s 200m or 300m are good for diving at depths, and only Diver's 300+ m are tailored for saturation diving in helium enriched environment.