threshold

Etymology

From Middle English threschwolde, threscholde, from Old English þresċold, þerxold, þrexwold (“doorsill, entryway”), from Proto-Germanic *þreskudlaz, *þreskūþlijaz, *þreskwaþluz, from Proto-Germanic *þreskaną, *þreskwaną (“to thresh”), from Proto-Indo-European *terh₁- (“to rub, turn”). Cognate with Low German Drüssel (“threshold”), dialectal German Drischaufel, Drissufle, Trüschübel (“threshold”), Danish tærskel (“threshold”), Norwegian terskel (“threshold”), Swedish tröskel (“threshold”), dialectal Swedish träskvald (“threshold”), Icelandic þröskuldur (“threshold”).

noun

1. The lowermost part of a doorway that one crosses to enter; a sill.
2. (by extension) An entrance; the door or gate of a house.
3. (by extension) Any end or boundary.
4. (figurative) The outset of something; the point of entry, or the beginning of an action.
   I arrived at last, did obeisance to my uncle, and told him everything. He thought it over and said: ' […] At the threshold of death, how dare I give you permission to go to England, to cross the seas? But I will not stand in your way. It is your mother's permission which really matters. If she permit you, then godspeed! Tell her I will not interfere. You will go with my blessings.' 1927-29, M.K. Gandhi, The Story of My Experiments with Truth, translated 1940 by Mahadev Desai, Part I, Chapter xi
   The first half of this century has been referred to as the golden age of medicine. To me it seems more probable that we are on the threshold of a much greater age. 1951 March, John W. Cline, “The Future of Medicine”, in Northwest Medicine, volume 50, number 3, Portland, Ore.: Northwest Medical Publishing Association, page 165
5. (aviation) The start of the landing area of a runway.
6. (engineering) The quantitative point at which an action is triggered, especially a lower limit.
7. The wage or salary at which income tax becomes due.
8. The point where one is mentally or physically vulnerable in response to a provocation or to other nuisances.