From Longman Dictionary of Contemporary Englishmetronomemet‧ro‧nome /ˈmetrənəʊm $ -noʊm/ noun [countable] 
APMa piece of equipment that makes a regular repeated sound like a clock, showing the speed at which music should be played
APMa piece of equipment that makes a regular repeated sound like a clock, showing the speed at which music should be playedExamples from the Corpus
metronome• They went back to their dressing-room in a hurry as soon as the act was over, and Arthur started a metronome.• He repeated it thousands of times, like a haywire metronome that had lost its beat.• They move their heads to follow the swinging balances, which rock like metronomes on H-1 and H-2.• Talmi is so surprised by the tempo that he taps a finger on his wristwatch to gauge the metronome marking.• But, with the metronome quality of these rulings, one or the other is always out of favor.• The rhythm of the camp is constant, a ticking metronome.• I trained it, with metronomes.Origin metronome (1800-1900) Greek metron ( → -METER) + -nomos “controlling” (from nomos “law”) 