Are yams and sweet potatoes the same?
Old English gretan "to come in contact with" (in sense of "attack, accost" as well as "salute, welcome," and "touch, take hold of, handle"), from West Germanic *grotjan (cf. Old Saxon grotian, Old Frisian greta, Dutch groeten, Old High German gruozen, German grüßen "to salute, greet"), perhaps originally "to resound" (via notion of "cause to speak"), causative of Proto-Germanic *grætanan, root of Old English grætan (Anglian gretan) "weep, bewail," from PIE *gher- "to call out." Greet still can mean "cry, weep" in Scottish & northern England dialect, though this might be from a different root. Grætan is probably also the source of the second element in regret. Related: Greeted; greeting.