From The Collaborative International Dictionary of English v.0.48 [gcide]:
Concertina \Con'cer*ti"na\, noun [From It. concerto a concert.] A small musical instrument on the principle of the accordion. It is a small elastic box, or bellows, having free reeds on the inside, and keys and handles on the outside of each of the two hexagonal heads.
From WordNet (r) 3.0 (2006) [wn]:
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