concertina

noun

1. 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.

   “That concertina was a wonder in its way. The handles that was on it first was wore out long ago, and he'd made new ones of braided rope yarn. And the bellows was patched in more places than a cranberry picker's overalls.”

   “Elsewhere, professionals could enthuse over new precision instruments capable, for instance, of measuring weights down to a tenth of a milligram, or over a host of self-registering thermometers and barometers, microscopes, typewriters, calculators and all sorts of technical and musical devices, including automatic concertinas, edeophones, auto-harps, bigophones and other long-forgotten objects.”

2. Something multiply folded like a concertina, such as a folded book, a bus door or a set of picture frames that are folded together.
3. Coiled barbed wire for use as an obstacle.
4. A type of booklet label, consisting of up to 32 pages of booklet as an insert.

verb

1. To become compressed into a shape reminiscent of a concertina.

   “The car concertinaed into the wall.”

   “Millions of years ago the mica schists surrounding the old Brandberg West Mine became folded and concertinaed by enormous horizontal pressures.”

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

   “This resulted in some fragmentation of the line as the boats in some cases closed to just 50 metres as they concertinaed in and out of sight of each other.”