What does concertina mean?

What does concertina mean?
The Deinition From A Dictionary Is Below-noun 1. a musical instrument resembling an accordion but having buttonlike keys, hexagonal bellows and ends, and a more limited range. 2. concertina wire.
-verb (used without object) 3. to fold, crush together, or collapse in the manner of a concertina: The car concertinaed when it hit the truck.
-verb (used with object) 4. to cause to fold or collapse in the manner of a concertina.
-adjective 5. of, pertaining to, or resembling a concertina: concertina pleats.
Origin:
appar. coined by the original instrument's inventor, English instrument-maker Charles Wheatstone (1802-75), who patented it in 1829; cf. concertino, seraphina a similar instrument