- any of various devices for measuring minute distances, angles, etc., as in connection with a telescope or microscope.
- a precision instrument with a spindle moved by a finely threaded screw, for the measurement of thicknesses and short lengths, commonly used by machinists for turning shafts or boring holes.
- any of various instruments or devices for the accurate measurement of distances or angles
- a type of gauge for the accurate measurement of small distances, thicknesses, diameters, etc. The gap between its measuring faces is adjusted by a fine screw, the rotation of the screw giving a sensitive measure of the distance moved by the face
