noun plural. 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.

noun plural. a draughtsman's or mechanic's square, having a graduated bar and adjustable jaw or jaws.

noun plural. See Vernier.

noun. A device used to measure thickness between two surfaces, especially for small or precise measurements.