crutch (n.)

Middle English crucche, "a support for the lame in walking consisting of a staff of proper length with a crosspiece at one end shaped to fit conveniently under the armpit," from Old English crycce "crutch, staff," from Proto-Germanic *krukjo (source also of Old Saxon krukka, Middle Dutch crucke, Old High German krucka, German Kröcke "crutch," related to Old Norse krokr "hook;" see crook (n.)).

Figurative sense of "a prop, a support" is first recorded c. 1600. As a verb, from 1640s.

Century Dictionary writes, "Akin to crook, with which in the Romance languages its derivatives are mingled" (Italian gruccia "crutch," crocco "hook" are Germanic loan-words).