Direct answer: The English word "threshold" comes from Old English þrescold (also spelled þerscwold, þeorscwold), a compound whose first element is related to Old English þrescan "to thresh, tread, or trample" and whose second element is an old Germanic board/wood element (‑wold/‑hold) meaning a plank or plank-like piece; together the compound originally meant the board or sill that is stepped on at a doorway.

Short derivation

  • Earliest attestations: Old English forms such as þrescold and þeorscwold appear in translations from around the 9th century.
  • First element: related to Old English þrescan ("to thresh"—to beat or tread grain), from Proto‑Germanic *þreskaną and ultimately the PIE root meaning to rub or turn; this reflects the idea of trampling or stepping.
  • Second element: a Germanic suffix or word (reconstructed as *‑wold / *‑wald / *‑hold in different accounts) meaning a plank, ridge, or piece of timber; in the compound it denotes the board at the foot of the doorway.

Why people once thought a different origin

  • Folk etymology suggested "threshold" came from "thresh" (straw/rushes put on floors) + "hold" (to hold the straw in), i.e., the board that kept straw inside the house; that story is appealing but linguistically unlikely because the compound predates that practice and the word parts better match the trampling/wood interpretation.

Cognates and sense development

  • Cognates exist across Germanic languages (Old Norse threskǫldr, medieval and modern forms in Scandinavian and German), showing it’s an inherited Germanic compound.
  • The meaning broadened from a literal door‑sill to abstract senses like a limit or point at which something begins (e.g., "threshold of pain" or "threshold of detection"), a typical semantic shift from physical boundary to figurative boundary.

Example (illustration): imagine a heavy plank worn smooth by centuries of feet—that plank is the original, literal threshold (step‑board) whose name preserves the action of treading.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.