chronometer

n. [ Gr. &unr_; time + -meter: cf. F. chronomètre. ] 1. An instrument for measuring time; a timekeeper. [ 1913 Webster ]

2. A portable timekeeper, with a heavy compensation balance, and usually beating half seconds; -- intended to keep time with great accuracy for use an astronomical observations, in determining longitude, etc. [ 1913 Webster ]

3. (Mus.) A metronome. [ 1913 Webster ]

Box chronometer. See under Box. --
Pocket chronometer, a chronometer in the form of a large watch. --
To rate a chronometer. See Rate, v. t. [ 1913 Webster ]