late 14c., "to lead, direct, conduct," from Old French guider "to guide, lead, conduct" (14c.), earlier guier, from Frankish *witan "show the way" or a similar Germanic source, from Proto-Germanic *witanan "to look after, guard, ascribe to, reproach" (source also of German weisen "to show, point out," Old English witan "to reproach," wite "fine, penalty"), from PIE root *weid- "to see." The form of the French word influenced by Old Provençal guidar (n.) "guide, leader," or Italian guidare, both from the same source. Related: Guided; guiding. Guided missile, one capable of altering course in flight, is from 1945.