Caliper definition1. The apparatus on disc brakes which hold the disc pads and straddles the disc. When actuated the pads press against the disc to stop or slow the vehicle.
2. On bicycles , the brake arms that reach around the sides of a wheel to press brake pads against the wheel rim.
3. An adjustable measuring tool that is placed around (outside caliper) or within (inside caliper) an object and adjusted until it just contacts. It is then withdrawn and the distance measured between the contacting points.