Essential Watch Terms

As you might suspect, the watch world has many more terms and essential language. If you think I missed something check the linked posts above and if you still think I missed something important, drop me a message.  Viel Spaß!

Automatic – A type of mechanical watch that is wound by the motion of the wearer. The movement of the wearer moves a rotor (counterweight) that powers the mainspring which turns the watch gears. So, instead of winding a crown you just need good old-fashioned movement.

Balance Wheel – A weighted wheel in a mechanical watch that spins at a constant rate. The wheel usually oscillates a fraction of a second per spin which drives the gears that end in the movement of the hands.

Barrel – A cylindrical housing inside a mechanical watch with an outer ring of gear teeth that contains the mainspring. The mainspring is attached to the inner wall of the barrel and a central arbor. The slow rotation of the barrel drives the gear train. The slow release of the mainspring is the power reserve of the watch. In some watches, additional barrels are added to expand the power reserve.

Bridge – A complementary part (often a plate or bar of metal) affixed to the mainplate which forms the frame of a watch movement.

Caliber – In modern watch making the term caliber is used as a synonym for the movement. In practice, many watchmakers will refer to the movement as “caliber ABC123” (caliber followed by movement identification ABC123). Historically, as in firearms, caliber referred to the diameter of the movement.

Chronograph – In watchmaking, this can refer to a type of watch or a complication of the watch. As a complication, it measures elapsed time i.e., a stopwatch. There is a multitude of variations of chronographs that have subdials measuring seconds, minutes or hours. Typically, a chronograph watch will have two pusher buttons on the watch.  The top pusher will start and stop the chronograph and the bottom pusher will reset the dials to zero.

Chronometer – A watch that has passed a series of tests administered by an official chronometer certification agency such as COSC.

Complication – Is a device in a watch that performs a specific function other than the actual telling of time. Examples would be calendars or chronographs

COSC – Also written as C.O.S.C, refers to Contrôle Officiel Suisse des chronomètres (Swiss Chronometer testing bureau.  This is a Swiss government-sponsored agency that tests watches submitted for testing.

Ébauche – In modern watchmaking, this is an unassembled, jeweled movement without the regulating parts, mainspring, dials or hands. Most of the remaining suppliers of ébauche are owned by ETA which is owned by the Swatch Group.

Exhibition Back – a transparent cover on the backside of the watch revelaing the inner workings.

Frequency – The number of vibrations, beats or semi-oscillations that a watch’s regulating mechanism makes over a set period of time. Most modern mechanical watches have a frequency of 21,600, 28,800 or 36,000 vibrations per hour (vph).  Most quartz watches have a frequency of 32,768 Hz which is 1,000 times faster than mechanical watch vibrations.

GMT – Greenwich Mean Time is the true meaning of the acronym.  For purposes of watches, GMT refers to the ability to track two time zones at once.

Guilloché – An engraved, decorative pattern on a watch dial often intricate interwoven lines.  Some guilloché are stamped on lower end watches.

Hacking Seconds – Also known as hack seconds.  A watch that hacks is one in which the second-hand stops when the crown is pulled out to the time setting position. This allows for the watch to be synchronized with other watches. When the crown is pulled a brake or lever stops the balance wheel.

Hairspring – A fragile, small spring attached to the balance wheel. The hairspring sits in the center of the balance wheel and rocks it at a very high speed. Vibrations per hour are used to track the speed. Higher vibrations will result in a second hand that moves smoother versus ticking.

Haute Horlogerie – French term translating to high watchmaking. It is a term used to identify a watch or watchmaker that demonstrates extreme proficiency in design, innovation, and finishing of watches.

Indices – The marks on a watch dial that are used in place of numerals at the hour marks. In high-end watches, the indices will be applied versus etched on the dial.

Jewels – In watches, jewels are not for decoration. Rather the synthetic rubies and sapphires are used as low friction bearings at critical points in a watch. The jewels against the metal parts of the watch lower the friction and extend life and increase the accuracy of a watch.

Linge – Is an old-school unit of measurement in watchmaking equivalent to 2.2558291 millimeters. Ligne is often represented with three prime marks such as 4‴.

Lume – Luminescence is the glow of certain parts of a watch such as the hands, indices or numerals. Typically, the lume is produced by phosphorescent material.

Magnetism – The metal pieces of a watch can be magnetized when exposed to a magnetic field. A metal hairspring can become magnetized and stick together which slows a watch. A watchmaker can reverse the problem.

Mainplate – The base where all the parts of a mechanical watch are mounted.

Manufacture D’Horologie – also shortened to ‘manufacture’ is a French term for a watchmaker that makes its own parts in-house versus assembling third party parts.

Moon Phase – An indicator (complication) of a watch that shows the phase of the moon waxing and waning.

Nato Strap – Also known as a G10 strap, is a nylon strap with a metal buckle and two metal keepers. Additionally, the Nato strap has an extra piece of nylon with a keeper at the end  This extra piece of nylon helps hold the watch in place and provides added protection should a spring bar fail.

Perpetual Calendar – A calendar mechanism (complication) that automatically adjusts for unequal lengths of the 12 months, including leap-year February. Most perpetual’s will be accurate until the year 2100 due to a quirk in the Gregorian calendar.

Power Reserve -The length of time a mechanical watch will run without the need to be rewound. Typically, the power reserve will be anywhere from 36 hours to an entire week.

Pusher – A push button on a chronograph watch that starts, stops and resets the chronograph.

Repeater – A watch that chimes the time when a button is pushed on the watch case. There are various repeaters that will tell the hour or as detailed as tell the time to the minute.

Retrograde – An indicator on a watch dial that is a partial circle. When the indicator goes the whole cycle it will reset back to zero. Retrogrades are often used for hours, minutes, or dates.

Screw Down Crown – A threaded winding crown that tightens to prevent water and dust from entering the watch.

Skeleton – shows off the inner working of the watch through a transparent or partially cut out dial.

Small Seconds – A small subdial separate from the minute and hour hands that track seconds.

Tourbillon – A typically expensive complication that houses the escapement in a rotating cage that is meant to counteract the effects of gravity and movement.

Winder – A box or case that gently rotates an automatic watch to continually engage the rotor keeping the watch fully wound when not being worn.

World Timer – A watch with a dial that can be adjusted to keep track of 24 different time zones with representative cities shown.

Zulu Strap – Similar to a Nato strap, these straps are nylon (typically thicker than Nato straps) with a metal buckle and two metal keepers.  Unline a Nato there is not an extra piece of nylon securing the watch case.

There you have it.  As I said at the top of the article, some terms were already covered in earlier posts and not repeated here.