D defs.my
Entry 2 senses Webster, 1913

Backstay

/(băk"stā`)/ · Back·stay · IPA
01 n. A rope or stay extending from the masthead to the side of a ship, slanting a little aft, to assist the shrouds in supporting the mast.
  1. 1.
    A rope or stay extending from the masthead to the side of a ship, slanting a little aft, to assist the shrouds in supporting the mast.(Naut.) [Often used in the plural.]
  2. 2.
    A rope or strap used to prevent excessive forward motion.