"small, keyed, bellows-like wind instrument," 1830, from German Akkordion, from Akkord "musical chord, concord of sounds," from a verb similar to Old French acorder "agree, be in harmony," from Vulgar Latin *accordare (compare Italian accordare "to attune a musical instrument;" see accord (v.)), with suffix on analogy of clarion, etc. Invented 1829 by piano-maker Cyrill Demian of Vienna. The type with a keyboard instead of buttons is a piano accordion. Related: Accordionist.

"portable, accordion-like musical instrument," 1835, from concert + fem. ending -ina. Invented 1829 by English inventor Professor Charles Wheatstone (who also invented the stereoscope and the Wheatstone bridge). Concertina wire attested by 1917, so called from similarity to the musical instrument.