said of a plant: to lose freshness and become limp; to droop
said of a person: to grow weak, tired, or faint; to languish
to cause (a plant or person) to wilt
alteration of dialect welk to become stale, of Low German origin. Although wilt was in use in British dialect at least as long ago as the 17th cent., it did not gain general currency in British English until the second half of the 19th cent.; it was then reintroduced from American English, where it had long been widespread