n.an adjustable stay from the foremast to the deck or bowsprit; controls the bending of the mast
英汉双解大词典
forestay/ˈfɔːˌsteɪ/
1.
N（名词）
an adjustable stay leading from the truck of the foremast to the deck, stem, or bowsprit, for controlling the motion or bending of the mast 前桅支索 [nautical]