accordion

Etymology

First attested in 1831. From German Akkordeon, from Akkord (“harmony”), from French accord, from Old French acorder, based on Italian accordare (“to tune”). See also accord.

noun

1. A box-shaped musical instrument with means of keys and buttons, whose tones are generated by play of the wind from a squeezed bellows upon free metallic reeds.
   A disreputable accordion that had a leak somewhere and breathed louder than it squawked. 1869, Mark Twain, Innocents Abroad
2. (graphical user interface) A vertical list of items that can be individually expanded and collapsed to reveal their contents.
3. (figurative) A set of items (concepts, links, or otherwise) that can be packed and unpacked cognitively, or their representation as a set of virtual objects.
   See also: telescoping

verb

1. (transitive, intransitive) To fold up, in the manner of an accordion
   Still in reverse, she goosed the gas and accordioned the running board a fraction of an inch more. December 29, 2000, Charles Dickinson, “Qi”, in Chicago Reader
   It accordioned down and he tugged the shirt around it so that it came free[…]. 2005, Cory Doctorow, Someone Comes to Town, Someone Leaves Town