An accordion is a bellow-driven [[instrument]]. It usually has a rectangular bellow and asymmetrical sides with keys sticking out on one side. Example: post #2466981

If the sides look symmetrical and the bellow is square, hexagonal or octagonal, it’s probably a [[concertina]] instead.

h4#external-links. External links

* Wikipedia article: "Accordion":[https://en.wikipedia.org/wiki/Accordion]

アコーディオン