"muscle contraction," late 14c., from Old French crampe, from a Frankish or other Germanic word (compare Old High German krapmhe "cramp, spasm," related to kramph "bent, crooked"), from a Proto-Germanic root forming many words for "bent, crooked," including, via French, crampon. Writer's cramp is first attested 1842 as the name of a physical affliction of the hand, in reference to translations of German medical papers (Stromeyer); also known as scrivener's palsy.

"metal bar bent at both ends," early 15c., from Middle Dutch crampe or Middle Low German krampe, both from the same Proto-Germanic root that yielded cramp, n.1. Metaphoric sense of "something that confines or hinders" first recorded 1719.

"to contract" (of muscles), early 15c., from cramp, n.1. Related: Cramped; cramping.

"to bend or twist," early 14c., from cramp, n.2 and Old French crampir. Later "compress forcibly" (1550s), and, figuratively, "to restrict" (1620s). Related: Cramped; cramping.