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 *wit- "to know" (cf. German weisen "to show, point out," Old English witan "to see"), from PIE *weid- "to see" (see vision). 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.