concertina

Noun

• A musical instrument, like the various accordions, that is a member of the free-reed family of musical instruments, typically having buttons on both ends.
• Something resembling a concertina, such as a folded book, a bus door or a set of picture frames that are folded together.
• Coiled barbed wire for use as an obstacle.
• A type of booklet label, consisting of up to 32 pages of booklet as an insert.

Verb

• to become compressed into a shape reminiscent of a concertina
• to be drawn closer and farther apart repeatedly, or up and down, as if situated on a working concertina's folds