Are yams and sweet potatoes the same?
1590s, variant of Middle English gonfanon (c.1300), from Old French gonfanon "knight's pennon" (12c.), from Old High German guntfano "battle flag," from Proto-Germanic *gunthja- "war," from PIE *gwhen- "to strike, kill" (see bane) + *fano "banner" (cf. Gothic fana "cloth"). Cognate with Old English guþfana, Old Norse gunnfani. Change of -n- to -l- by dissimilation.