chronometer

UK: /krɒˈnɒmɪtə^r/ US: (krə nom′i tər)

WordReference Random House Unabridged Dictionary of American English © 2026

chro•nom•e•ter  (krə nom′i tər), n. 

1. Time a timepiece or timing device with a special mechanism for ensuring and adjusting its accuracy, for use in determining longitude at sea or for any purpose where very exact measurement of time is required.
2. Time any timepiece, esp. a wristwatch, designed for the highest accuracy.

• 1705–15; chrono- + -meter

chron•o•met•ric  (kron′ə me′trik), chron′o•met′ri•cal, adj.  chron′o•met′ri•cal•ly, adv. 

Collins Concise English Dictionary © HarperCollins Publishers::

chronometer / krəˈnɒmɪtə/ noun

1. a timepiece designed to be accurate in all conditions of temperature, pressure, etc, used esp at sea

chronometric / ˌkrɒnəˈmɛtrɪk/, ˌchronoˈmetrical adjective

ˌchronoˈmetrically adverb