\Pre*vent"er\, n.
1. One who goes before; one who forestalls or anticipates
   another. [Obs.] --Bacon.
2. One who prevents or obstructs; a hinderer; that which
   hinders; as, a preventer of evils or of disease.
3. (Naut.) An auxiliary rope to strengthen a mast.
{Preventer bolts}, or {Preventer plates} (Naut.), fixtures
   connected with preventers to re["e]nforce other rigging.
{Preventer stay}. (Naut.) Same as {Preventer}, 3.