New, Antique and Vintage Watch Glossary Of  Terms. Read before you join an auction!
Includes terms such as OVER WOUND, which is a false and misleading term......

A

Annual calendar
A watch displaying the day, date, month, and 24 hours that adjusts automatically for short and long months. An annual calendar requires only a single manual correction per year from the end of February to the 1st of March.

Aperture (or dial window)
A small opening in a dial plate through which various information is displayed: date, hours, day of the week.

Applique
Numerals or symbols stuck or riveted to a dial.
Analog
This is a watch that you can tell the time using hour and minute hands.
Analog - Digital
This is a watch that has both mechanical hands and a digital display in numbers.
Aperture
Where the date is displayed within the dial of the watch

Assembling and finishing
The process of assembling and testing all parts of a watch.

Atmosphere (Atm)
measure of the water resistance of a watch. Unit of pressure used in watch making to indicate the level of water resistance.

Automatic Watch
An automatic watch contains a self-winding, mechanical watch movement that is wound by the movement of the wearer. A heavy pivoted rotor turning back and forth transmits its energy to the spring by means of an appropriate mechanism.
Automatic Movement
An automatic watch has a mechanical movement and does not need to be regularly wound. Its power comes from the movement of your wrist as you wear it. Most automatic watches have a power reserve of up to 36 hours.
B
Back
the part that rests on the wearer’s arm and can be either pressed or screwed onto the case
Battery Reserve Indicator
Some Quartz watches have this function. The watch will indicate when the battery is nearing the end of its life. This can often be seen by observing the movement of the hands which will jump 2-4 seconds depending upon the make and model.
Bezel
The Bezel is the ring around the dial of the watch. Often it serves as other functions (as is the case with a Bi-directional Rotating Bezel). It is often made of Stainless Steel or Gold (or Gold Plated). The part of the case that holds the crystal in place
Bracelet
Linked metal strap on a watch. You can change the length by removing links.
Brushed Steel
Stainless Steel with a Matt 'brushed' effect finish.
Buckle
The buckle joins the strap together and is often made of the same material as the case of the watch.

Balance
A wheel-like device which, by rotating back and forth, regulates the gear train movement as uniform as possible.

Balance-cock
A separate bridge holding the balance and regulator assemblies.

Barrel
Thick wheel featuring a toothed disc on one face and containing the mainspring of a watch movement.

Bolt, or slide
An operating part, on repeater watches, made of the same metal as the case and shifted along the caseband with the fingernail. The repeating-slide winds the spring of the striking mechanism.

Bottom plate
A metal plate bearing the bridges and various parts of the movement.

Bridge (or bar, or cock)
A metal movement part that is attached to a bottom plate and holds at least one bearing of a rotating part.