From Longman Dictionary of Contemporary Englishtrombonetrom‧bone /trɒmˈbəʊn $ trɑːmˈboʊn/ noun [countable] 
APMa large metal musical instrument that you play by blowing into it and sliding a long tube in and out to change the notes —trombonist noun [countable]
APMa large metal musical instrument that you play by blowing into it and sliding a long tube in and out to change the notes —trombonist noun [countable]Examples from the Corpus
trombone• From behind it we could hear the chirps and roars of invisible clarinets and trombones tuning up.• Then from 1968-70. he played bass trombone and tuba with Doe Severinson s band.• The bass trombone and tuba play the bass in octaves.• His only modest joy in life comes from playing trombone with a third-rate jazz band in a seedy neighborhood pub.• This year a mere sprat of a northern lass won my heart playing hers out on a mighty and sonorous trombone.• The trombone does a dipping glissando, I get some laughs.• The trombones should only be used for such bass parts as suit them well.Origin trombone (1700-1800) Italian tromba “trumpet” 