METRONOME
metronome
(noun) clicking pendulum indicates the exact tempo of a piece of music
Source: WordNet® 3.1
Etymology
Noun
metronome (plural metronomes)
(music) A device, containing an inverted pendulum, used to mark time by means of regular ticks at adjustable intervals; an electronic equivalent that emits flashes.
Anagrams
• monometer, monotreme, nomotreme
Source: Wiktionary
Met"ro*nome, n. Etym: [Gr. métronome, It. metronomo.]
Definition: An instrument consisting of a short pendulum with a sliding
weight. It is set in motion by clockwork, and serves to measure time
in music.
Source: Webster’s Unabridged Dictionary 1913 Edition