ac·cor·di·on (ə-kôr'dē-ən) n. A portable wind instrument with a small keyboard and free metal reeds that sound when air is forced past them by pleated bellows operated by the player. adj. Having folds or bends like the bellows of an accordion: accordion pleats; accordion blinds.
[German Akkordion, from Akkord, chord, from French accord, harmony, from Old French acorder, to accord, from Medieval Latin accordāre, to bring into agreement; see accord.] ac·cor'di·on·ist n.