<p><strong>Noun</strong></p><ul><li>a musical instrument resembling an accordion but having buttonlike keys, hexagonal bellows and ends, and a more limited range: concertina.</li><li>concertina wire.</li></ul><p><strong>Verb</strong></p><ul><li>(used without object) to fold, crush together, or collapse in the manner of a concertina: The car concertinaed when it hit the truck.</li><li>(used with object) to cause to fold or collapse in the manner of a concertina.</li></ul><p><strong>Adjective</strong></p><ul><li>of, relating to, or resembling a concertina: concertina pleats.</li></ul>