Chronometer

Part of speech: noun (n.)

1. An instrument for measuring time; a timekeeper.

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.

3. A metronome. Box chronometer. See under Box. -- Pocket chronometer, a chronometer in the form of a large watch. -- To rate a chronometer. See Rate, v. t.