Definitions

1. noun

A clock or watch that is accurate to a high degree, especially one used to regulate other clocks or to time events with great precision.

“The chronometer was used to measure the exact time of the sunrise.”

2. noun

A device for measuring the time interval between two events, such as the time of a celestial event or the time of a sound.

“The astronomers used a chronometer to measure the time interval between the supernova’s explosion and its observation.”