Compasses \Com"pass*es\, n., pl. An instrument for describing circles, measuring figures, etc., consisting of two, or (rarely) more, pointed branches, or legs, usually joined at the top by a rivet on which they move.

Note: The compasses for drawing circles have adjustable pen points, pencil points, etc.; those used for measuring without adjustable points are generally called dividers. See Dividers.

Bow compasses. See Bow-compass.

Caliber compasses, Caliper compasses. See Calipers.

Proportional, Triangular, etc., compasses. See under Proportional, etc.

Source: Webster's Revised Unabridged Dictionary (1913)