D defs.my
Entry 1 sense Webster, 1913

Calipers

/kăl'-əp-ẽrz/ · Cal·i·pers · IPA /ˈkæl.ɪ.pɚz/
01 n. pl. An instrument, usually resembling a pair of dividers or compasses with curved legs, for measuring the diameter or thickness of bodies, as o…
  1. 1.
    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. Also: caliper compasses, caliber compasses
Phrases & compounds
Caliper square — a draughtsman's or mechanic's square, having a graduated bar and adjustable jaw or jaws.
Vernier calipers — See Vernier.