Threshold \Thresh"old\, n. [OE. threswold, [thorn]reshwold, AS. [thorn]rescwald, [thorn]erscwald, [thorn]erscold, [thorn]rescold, fr. [thorn]rescan, [thorn]erscan, to thresh; akin to Icel. [thorn]reskj["o]de, [thorn]r["o]skuldr, Sw. tr["o]skel, Dan. t[ae]rskel. See Thrash.]

1. The plank, stone, or piece of timber, which lies under a door, especially of a dwelling house, church, temple, or the like; the doorsill; hence, entrance; gate; door.

2. Fig.: The place or point of entering or beginning, entrance; outset; as, the threshold of life.

Source: Webster's Revised Unabridged Dictionary (1913)