Watch lexicon

  • Watches Lexicon

You’ve just browsed through our articles, don’t understand what’s being said on the forums or online shops? Do you feel like perfecting or rediscovering your watchmaking vocabulary? If you miss certain words or if you forget certain definitions, don’t worry, because it’s quite normal. Just like the automobile, watchmaking includes a multitude of technical terms that take time to master.

Definitions to know in watchmaking

If you want to perfect your watchmaking culture, you’ve come to the right place! Le Petit Poussoir has gathered together the most important terms to help you navigate through the lexical field of timepieces. Take your time, it’s essential and even exciting !



Abbreviation for “normal atmosphere”, ATM is a unit of pressure indicating the water resistance of a watch. For example, a watch with a water-resistance of 10ATM can withstand a pressure of 10 bar, or 100 meters deep. However, this is an indication that should not be taken at face value. For example, diving requires a minimum capacity of 20ATM.



A mobile element, generally circular in shape, it is the organ that regulates the watch. It oscillates on its axis of rotation and is coupled to the balance spring, which allows it to make a perfectly regular to-and-fro movement, called oscillation (the famous “ticking”). In the case of quartz watches, the balance-spring is replaced by an electric motor powered by a battery. Bar



Unit of reference atmospheric pressure, 1 bar or 1013 hectopascals, it is a term used to indicate the water-resistance of a watch (see also ATM).



The barrel is an assembly consisting of a cylindrical box and a gearwheel closed by a lid. It enables the energy produced by the winding system to be accumulated and then redistributed to the various gears of the movement.



The case (or box) is the main protection of a watch and protects the mechanism from shocks, humidity and dust. It consists of a main part called the case middle containing the movement, the dial and the hands, to which the various external elements are attached.

Ardillon Buckle


The pin buckle is the most classic type of clasp, consisting of a metal point hinged on a buckle allowing the bracelet to be closed by means of a perforation in the pierced strand.

Folding clasp


The folding clasp is a hinged clasp that unfolds when it is opened. In particular, it allows the watch to float around the wrist in the event of accidental opening.



The dial is a generally metallic piece on which various indications such as hours, minutes and seconds are displayed.



The calibre is a term designating the type of movement of a watch. Originally, the word echoed the layout and dimensions of the various components of the movement, then its shape and origin, and finally the movement itself.



The caseband is one of the three main parts of the case that houses the movement. It is located between the caseback and the bezel of the watch.



A chronograph is a watch that indicates hours, minutes and seconds and has a hand that can be started and stopped at the touch of a button to measure the duration of an event. It usually has hour and minute counters that add up the revolutions of the chronograph hand.



By definition, the term coaxial means “on the same axis” and therefore refers to a movement with several hands on the same axis (hours, minutes, seconds).



The complication refers to any other function that a watch may have other than the indication of hours, minutes and seconds. This includes, for example, the perpetual calendar, tourbillon, time zones, chronograph or moon phases.



Solidly attached to the caseband and located at the ends of the case, the lugs serve to attach the bracelet to the watch. The small barrette that fits into them thanks to small holes, also passing through the inside of the bracelet to hold it in place, is also called the lugs.



The crown is a button on the outside of the case that allows the movement to be wound manually and the time of the watch to be set.



Also known as “fly-back”, fly-back is a function that was developed for airplane pilots to measure the duration of an event and reset it to zero without having to stop the chronograph hand.



Abbreviation meaning “Greenwich Mean Time”. The term refers to solar time at the meridian of the Greenwich Observatory in England, which is a 24-hour calendar time starting at midnight. On a watch, the GMT function refers to the display of a second time zone simultaneously with the local time.

Grande Seconde


The large second refers to the second hand, which is the seconds hand at the centre of a watch. This term contrasts with the small seconds sometimes placed in a small dial at 6 o’clock.



The index refers to certain hour markings, i.e. the markers that have gradually replaced the Roman or Arabic numerals generally ranging from 1 to 12 on the dial.



By definition, luminescence refers to the emission of light rays. In watchmaking, it is the material covering the index and hands that enables the time to be read in the dark. Tritium was the material used in the past but was replaced by the LumiNova system because of its radioactive properties.



LumiNova is a luminous paste composed of tritum bulbs that allows light to be stored and then reflected when plunged into darkness. This material has been used to remove the radium salts present in tritium and thus displace the radioactive property of tritium.



The bezel is one of the main elements of the case. It is located on the upper part, above the case middle, and carries the watch glass. The bezel can be rotated to indicate various information such as the duration of an event. When it is unidirectional, it rotates in one direction only, especially for diving watches.



A symbol of quality in watchmaking, a manufacture designates a factory producing its products in an artisanal manner, i.e. almost entirely. This term notably echoes a movement entirely developed by a brand.



The hammer is a piece of metal that strikes the timbres to make them vibrate and thus produce sounds. It is a piece found in striking watches.

Mechanical Watch


A mechanical watch, as opposed to a quartz watch, is a watch that runs without batteries. It is driven by a manually-wound movement that needs to be wound every day by turning the crown, or an automatic movement that is wound by the movements of the wearer via a rotor rotating around an axis.



The movement of a watch refers to all the parts and mechanism that make it work. The different types of movements are called calibres.



NATO bracelets were developed in 1973 at the request of the British Ministry of Defence, which was looking for a durable bracelet to equip its armies. This military origin still resounds in their name: North Atlantic Treaty Organization (NATO). 

Governing Body


Regulators, also known as governor, refer to the balance wheel and balance spring that operate with the anchor escapement. They enable the time to be counted and divided into hours, minutes and seconds.



The term perpetual refers to the perpetual calendar, i.e. the display of the date by its number. The perpetual calendar, on the other hand, is a type of complication that allows the day of the month as well as the month to be displayed on the dial of a mechanical watch. It takes into account irregular months of 31, 30, 29 or 28 days and leap years.

Moon Phases


Moon phases are a watchmaking complication that allows the various moon phases to be displayed on the dial of a watch. A lunation is divided into four phases: new moon, first quarter, full moon and last quarter, completing a complete cycle in 29 days, 12 hours, 44 minutes and 2.8 seconds.



Push-button refers to a button that is operated to set a mechanism in motion. It can be used, for example, to open a cover or start/stop a chronograph.



The calendar is a mechanism that allows the date of the day to be displayed on the dial of a watch. If it is perpetual, it automatically takes into account the months of 31 and 30 days as well as 28 and 29 days in February and leap years thanks to a mechanical memory.



The winder is a small stem connected to a wheel often referred to as the winding crown, allowing a watch to be wound manually or automatically. This part is used to either re-tension the spring or wind the weight of the clocks.

Minute Repeater


The minute repeater is a complication allowing the wearer of the watch to know, on demand, the exact time without looking at the dial. It is a particularly difficult complication which, thanks to a small hammer striking a miniature bell, indicates the time via low and high notes.

Power Reserve


Power reserve refers to the amount of time a watch runs without needing to be wound, or worn in the case of an automatic watch. As a general rule, mechanisms have a power reserve of approximately forty hours.



In watchmaking, the spring is a strip of hardened and blued steel, or of another special composition, wound inside the barrel. It is the mechanical energy source of a watch.



Ruby is a red gemstone made of corundum, aluminium oxide, of great hardness (2nd hardest mineral after diamond). It has given its name to a timepiece whose function is to reduce friction at certain points of the movement.



Sapphire glass is a virtually scratch-resistant material that protects the dial and hands of a watch. Some luxury models even use it to replace the case back.

Second Death


Characteristic of quartz watches, deadbeat seconds refers to the movement of a hand moving at the rate of one jump per second. In mechanical watchmaking, the deadbeat second is a true technical feat.



The balance-spring is a small spiral spring (part of the regulating organ) used to regulate the movement of a watch. It returns the balance to its initial position to start a new oscillation. Its quality has a great impact on the accuracy of the time given.



Also known as a skeleton movement, the skeleton is an aesthetic technique in which certain parts of a watch have been half-opened in order to reveal its organs.



The tachometer is an instrument for measuring speed. This sports meter has a scale dial that is used to calculate an average speed based on the time it takes to cover a given distance (often 1,000 metres).



A mechanical device developed by Abraham-Louis Breguet in 1801 in order to compensate for deviations in rate caused by the Earth’s gravity in a vertical position, the tourbillon contains the components enabling the balance to move back and forth in a small mobile cage in the centre of the watch making one revolution per minute. It is a very complex movement that has made it possible to improve the precision of mechanical watches.

Second hand


The second hand is the name given to the seconds hand which, advancing in jerks and turns, follows the oscillations of the balance. The large second hand is fixed in the centre of the dial while the small second hand is placed on a specific dial.

Words to add to this watchmaking lexicon?

Can’t find the answer to your question? An important word seems to be missing? Do not hesitate to contact us to let us know. Our team will take care of updating this watchmaking lexicon so that it is always more complete over time.