Hairbreadth /(-brĕdth)/

Hair·breadth

Hairbreadth
  1. The diameter or breadth of a hair; a very small distance; sometimes, definitely, the forty-eighth part of an inch.
    Every one could sling stones at an hairbreadth and not miss.
    — Judg. xx. 16.

Hairbreadth

a.
  1. Having the breadth of a hair; very narrow; as, a hairbreadth escape.