Noun
An instrument for measuring time; a timekeeper.
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.
A metronome.
Source: Webster's dictionaryA chronometer differs from a spring-driven watch principally in that it contains a variable lever device to maintain even pressure on the mainspring, and a special balance designed to compensate for temperature variations. Source: Internet
A nautical almanac and a marine chronometer are used to compute the subpoint on earth a celestial body is over, and a sextant is used to measure the body's angular height above the horizon. Source: Internet
A mariner with a chronometer could check its reading using a lunar determination of Greenwich time. Source: Internet
A spring-driven chronometer is set approximately to Greenwich mean time (GMT) and is not reset until the instrument is overhauled and cleaned, usually at three-year intervals. Source: Internet
Gould wrote The Marine Chronometer published in 1923, which covered the history of chronometers from the Middle Ages through to the 1920s, and which included detailed descriptions of Harrison's work and the subsequent evolution of the chronometer. Source: Internet
Also, many merchant mariners would make do with a deck chronometer at half the price. Source: Internet