The Collaborative International Dictionary of English v.0.48:

Waterproof \Wa"ter*proof`\, a.
   Proof against penetration or permeation by water; impervious
   to water; as, a waterproof garment; a waterproof roof.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Waterproof \Wa"ter*proof`\, n.
   1. A substance or preparation for rendering cloth, leather,
      etc., impervious to water.
      [1913 Webster]

   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.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Waterproof \Wa"ter*proof`\, v. t.
   To render impervious to water, as cloth, leather, etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

waterproof
    adj 1: not permitting the passage of water [syn: rainproof,
           waterproof, waterproofed]
    n 1: any fabric impervious to water
    2: a water-resistant coat [syn: raincoat, waterproof]
    v 1: make watertight; "Waterproof the coat"