The Collaborative International Dictionary
caliper compasses
Calipers \Cal"i*pers\, n. pl. [Corrupted from caliber.] An instrument, usually resembling a pair of dividers or compasses with curved legs, for measuring the diameter or thickness of bodies, as of work shaped in a lathe or planer, timber, masts, shot, etc.; or the bore of firearms, tubes, etc.; -- called also caliper compasses, or caliber compasses.
Caliper square, a draughtsman's or mechanic's square,
having a graduated bar and adjustable jaw or jaws.
--Knight.
Vernier calipers. See Vernier.