*preventer*

n. 1. One who goes before; one who forestalls or anticipates another. [ Obs. ] Bacon. [ 1913 Webster ]

2. One who prevents or obstructs; a hinderer; that which hinders; as, a preventer of evils or of disease. [ 1913 Webster ]

3. (Naut.) An auxiliary rope to strengthen a mast. [ 1913 Webster ]

Preventer bolts, or
Preventer plates (Naut.), fixtures connected with preventers to reënforce other rigging. --
Preventer stay. (Naut.) Same as Preventer, 3. [ 1913 Webster ]