D defs.my
Entry 1 sense Webster, 1913

Backsight

/(băk"sīt`)/ · Back·sight · IPA
01 n. The reading of the leveling staff in its unchanged position when the leveling instrument has been taken to a new position; a sight directed…
  1. 1.
    The reading of the leveling staff in its unchanged position when the leveling instrument has been taken to a new position; a sight directed backwards to a station previously occupied. Cf. Foresight, n., 3.(Surv.) See: Foresight