Real Dictionary

caliper
Calipers are an instrument consisting of two long, thin pieces of metal joined together at one end, and are used to measure the size of things.
Calipers are devices consisting of metal rods held together by straps, which are used to support a person's legs when they cannot walk properly.

caliper in American English
an instrument consisting of a pair of movable, curved legs fastened together at one end, used to measure the thickness or diameter of something: there are inside calipers and outside calipers
intransitive verb: to use calipers
noun: an instrument for measuring thicknesses and internal or external diameters inaccessible to a scale, consisting usually of a pair of adjustable pivoted legs
transitive verb: to measure with calipers

caliper in Automotive Engineering
noun: A caliper is the mechanism in a disk brake system that uses a pinching action to cause the brake pads to press onto the disk.

caliper in British English
noun

caliper in Mechanical Engineering
noun: A caliper is a measuring device that holds the object to be measured between two metal jaws.