Chronometer \Chro*nom"e*ter\, n. [Gr. ? time + -meter: cf. F. chronom[`e]tre.]

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. (Mus.) 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.

Source: Webster's Revised Unabridged Dictionary (1913)