accordion

As a noun accordion

is a small, portable, keyed wind instrument, whose tones are generated by play of the wind from a squeezed bellows upon free metallic reeds.

As a verb accordion

is (intransitive) to fold up, in the manner of an accordion.

As an adjective accordionlike is

resembling an accordion.

Melodeon is a hypernym of accordion.

As nouns the difference between accordion and melodeon

is that accordion is a small, portable, keyed wind instrument, whose tones are generated by play of the wind from a squeezed bellows upon free metallic reeds while melodeon is a music hall.

As a verb accordion

is to fold up, in the manner of an accordion.