Definify.com
Webster 1913 Edition
Backstay
Back′stayˊ
(băk′stāˊ)
, Noun.
[
Back
, a. or n. + stay
.] 1.
(Naut.)
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.
[Often used in the plural.]
2.
A rope or strap used to prevent excessive forward motion.