Caliber
In watch-making, the term designates the shape of the movement and the bridges, the origin, or the designer of the movement. Combined with an identifier, the term calibre unambiguously designates a specific movement.
Since the early 18th century, the calibre of a movement has denoted the positioning and size of its different components, notably the wheel-train and the barrel. Today the term is used more generally to refer to the shape of the movement, its origins or its constructor.
Also see caliber-list.