Chronometer /(?)/

Chro·nom·e·ter

Chronometer

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. (Mus.)

Phrases & Compounds
Box chronometer
See under Box.
Pocket chronometer
a chronometer in the form of a large watch.
To rate a chronometer
See Rate, v. t.