"to press tightly" (trans.), 1719; "to become wedged" (intrans.), 1706, of unknown origin, perhaps a variant of Middle English cham "to bite upon something; gnash the teeth" (late 14c.; see champ (v.)). Of a malfunction in the moving parts of machinery by 1851. Sense of "cause interference in radio signals" is from 1914. Meaning "play in a jam session" is from 1935. Related: Jammed; jamming. The adverb is recorded from 1825, from the verb; jam-packed is from 1901, earlier jam-full (1830).
early 14c., "room where wearing apparel is kept," earlier "a private chamber" (c. 1300), from Old North French warderobe, wardereube (Old French garderobe) "dressing-room, place where garments are kept," from warder "to keep, guard" (from Proto-Germanic *wardon "to guard," from suffixed form of PIE root *wer- (3) "perceive, watch out for") + robe "garment" (see robe (n.)). Meaning "a person's stock of clothes for wearing" is recorded from c. 1400. Sense of "movable closed cupboard for wearing apparel" is recorded from 1794. Meaning "room in which theatrical costumes are kept" is attested from 1711. Wardrobe malfunction is from 2004.
