Source : Webster's Revised Unabridged Dictionary (1913)

Waterproof \Wa"ter*proof`\, a.
   Proof against penetration or permeation by water; impervious
   to water; as, a waterproof garment; a waterproof roof.

Waterproof \Wa"ter*proof`\, n.
   1. A substance or preparation for rendering cloth, leather,
      etc., impervious to water.

   2. Cloth made waterproof, or any article made of such cloth,
      or of other waterproof material, as rubber; esp., an outer
      garment made of such material.

Waterproof \Wa"ter*proof`\, v. t.
   To render impervious to water, as cloth, leather, etc.

Source : WordNet®

waterproof
     adj : not permitting the passage of water [syn: {rainproof}, {waterproofed}]

waterproof
     n 1: any fabric impervious to water
     2: a water-resistant coat [syn: {raincoat}]
     v : make watertight; "Waterproof the coat"