The Collaborative International Dictionary of English v.0.48:
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
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