CONCERTINA

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.

To become compressed into a shape reminiscent of a concertina

"The car concertinaed into the wall."

To be drawn closer and farther apart repeatedly, or up and down, as if situated on a working concertina's folds