chronometer
nounUK /krəˈnɒm.ɪ.tər/
US /krəˈnɑː.mə.t̬ɚ/
A chronometer is a very exact clock that keeps time perfectly.
The sailor checked the chronometer to find out the ship's position.
RELATED WORDS
OTHER MEANINGS
2. A highly accurate clock used especially for scientific or navigational purposes.
The observatory's chronometer was calibrated daily against the stars.
3. A watch that has passed official precision tests.
He wore a certified chronometer that lost only a second a month.
4. Any instrument for measuring time precisely.
The lab used a chronometer to time the chemical reaction.