Glossary: Understand watch terminology

What is a bezel? What does GMT mean? And what’s the difference between an automatic and a quartz watch? Here’s a simple guide.

The world of watches can feel overwhelming for beginners, as it’s filled with specialist terms. Once you know the most common expressions, it becomes much easier to understand reviews, sales listings, and conversations among collectors.

Here’s a glossary with the key concepts to help you navigate mechanical watches, complications, and design details.

Key terms every enthusiast should know

Automatic – a mechanical watch powered by the natural movement of the wrist. No battery required.

Bezel – the ring around the crystal. On dive watches it often rotates to measure elapsed time, while on GMT watches it’s used to read an additional time zone.

Complication – any function beyond basic hours and minutes. Examples include chronographs, moonphases, perpetual calendars, and GMT displays.

COSC – short for Contrôle Officiel Suisse des Chronomètres. A Swiss certification guaranteeing chronometer-level precision.

GMT – stands for Greenwich Mean Time. A GMT watch has an additional hand that allows the wearer to track two or more time zones simultaneously. Popular among travelers and pilots.

Lugs – the horns that connect the case to the strap or bracelet. The distance between them defines the strap size.

Lume – luminescent material applied to hands and markers to make the watch readable in the dark. Often Super-LumiNova today, previously tritium or radium.

Movement – the mechanical engine that powers the watch. Can be manual-wind, automatic, or quartz.

Quartz – watches powered by a battery and a vibrating quartz crystal. Often more accurate than mechanical watches, though generally less prestigious.

Tourbillon – a high-end complication where the balance wheel and escapement rotate in a cage. Originally designed to counteract the effect of gravity.

A fast track into watch culture

For newcomers and curious enthusiasts, this glossary is a quick way to understand the language of watchmaking. Knowing what terms like bezel, complication, and lume mean makes it easier to choose the right watch – and to understand what you’re paying for.

It also makes the secondary market more accessible, as auction houses and dealers use precise terminology. A basic glossary can therefore be an essential tool for collectors.