accordion

noun

1. A box-shaped musical instrument played by compressing or expanding its bellows while pressing its buttons or its keys, causing pallets to open, which allow air to flow across strips of brass or steel (reeds).

   “A disreputable accordion that had a leak somewhere and breathed louder than it squawked.”

2. A vertical list of items that can be individually expanded and collapsed to reveal their contents.
3. (attributive, figuratively)Something, or set of things (concepts, etc), which can be expanded (or extended) and collapsed, like the musical instrument's pleated, folding bellows.

   “See also: telescoping”

   “"Accordion" skirts are named from the musical instrument of that title, because the peculiar plaiting draws out and falls together again, in the same kind of folds, and with the same effect.”

   “During the 1980s, accordion skirts became a popular style. Near the end of one winter season, I found a suit with a blazer-style jacket and an accordion-pleated skirt on sale at one of Birmingham's better department stores and placed it on layaway[…]”

   “[…] lugging their accordion cameras and bulky tripods from platform to hillock to ladder—even to the rooftop of a moving supply train—seeking to claim the most advantageous site for recording tomorrow's event.”

   “I see myself losing you when the truth is we've just planted the pink bud of a love affair. There is no relationship here, and yet I look around this place and I have the disorienting sensation that I've been here for years. As if it's an intimate cove of my history and an accordion of memories lives here, only just beginning to unfold.”

verb

1. (intransitive, transitive)To fold up, in the manner of an accordion

   “I slit the wrapping with my pocketknife and the clothesline accordioned out in stiff loops.”

   “Still in reverse, she goosed the gas and accordioned the running board a fraction of an inch more.”

   “It accordioned down and he tugged the shirt around it so that it came free[…].”