threshold (n.) Look up threshold at Dictionary.com
Old English þrescold, þærscwold, þerxold "doorsill, point of entering," first element related to Old English þrescan (see thresh), with its original sense of "tread, trample." Second element of unknown origin and much transformed in all the Germanic languages; in English it probably has been altered to conform to hold, but the oft-repeated story that the threshold was a barrier placed at the doorway to hold the chaff flooring in the room is mere folk etymology. Cognates include Old Norse þreskjoldr, Swedish tröskel, Old High German driscufli, German dialectal drischaufel.