chronometer

American  

[kruh-nom-i-ter] / krəˈnɒm ɪ tər /

noun

1. 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. any timepiece, especially a wristwatch, designed for the highest accuracy.

---

chronometer British  

/ krəˈnɒmɪtə, ˌkrɒnəˈmɛtrɪk /

noun

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

---

chronometer Scientific  

/ krə-nŏm′ĭ-tər /

1. An extremely accurate clock or other timepiece. Chronometers are used in scientific experiments, navigation, and astronomical observations. It was the invention of a chronometer capable of being used aboard ship, in 1762, that allowed navigators for the first time to accurately determine their longitude at sea.

---

Other Word Forms

• chronometric adjective
• chronometrical adjective
• chronometrically adverb

Etymology

Origin of chronometer

First recorded in 1705–15; chrono- + -meter

Explanation

A chronometer is a type of device that measures time in a manner that is highly accurate — not your average, ordinary watch. A chronometer is an exceptionally precise and stable timepiece that keeps accurate time even under harsh conditions. Marine chronometers, for example, must maintain accuracy despite the temperature fluctuations, humid conditions, and rocking motion that are common on ships at sea. The first practical marine chronometer was invented by John Harrison in the 18th century; it enabled navigators to accurately determine longitude, thus making maritime travel much safer. The word chronometer is built from Greek roots chronos, "time," and metron, "measure."

Example Sentences

By the story’s chronometer, a mere eight months had passed.

From Salon • Nov. 24, 2025

Plenty of interactive exhibits brings the voyage to life, including hands-on experimentation with a chronometer and Fresnel lens, outtakes from the duo’s journal, and short films.

From Seattle Times • Apr. 13, 2022

The magnetic compass, gunpowder, the printing press, the chronometer, the cotton gin, the steam engine and the water wheel are among the many examples.

From Scientific American • Aug. 24, 2020

The instruments on board – chronometer, thermometer, barometer, compass – were, at the time, state-of-the-art.

From Reuters • Dec. 11, 2019

The big box chronometers on the ship had been abandoned at Dump Camp, but Worsley had chronometer watches.

From "Shipwreck at the Bottom of the World" by Jennifer Armstrong