What is "preventer plates"

Preventer \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.