caliper

noun

• 1 (calipers) an instrument for measuring external or internal dimensions, having two hinged legs resembling a pair of compasses and in-turned or out-turned points.
• (also caliper rule) an instrument for measuring having one linear component sliding along another, with two parallel jaws and a vernier scale.
• (also brake caliper) a motor-vehicle or bicycle brake consisting of two or more hinged components.

• 2 (also caliper splint) a metal support for a person’s leg.