Emily Dickinson Lexicon

THRESH'OLD, n. [Sax. thærscwald; G. thürschwelle; Sw. tröskel; Ice. throsulldur. The Saxon and Swedish words seem by their orthography to be connected with thrash, thresh, and the last syllable to be wald, wood; but the German word is obviously compounded of thür, door, and schwelle, sill; door-sill.]

1. The door-sill; the plank, stone or piece of timber which lies at the bottom or under a door, particularly of a dwelling-house, church, temple or the like; hence, entrance; gate; door.
2. Entrance; the place or point of entering or beginning. He is now at the threshold of his argument. Many men that stumble at the threshold. Shak.