I. ˈwȯ-tər-ˌprüf, ˈwä- adjective
Date: 1736
: impervious to water ; especially : covered or treated with a material (as a solution of rubber) to prevent permeation by water
• wa·ter·proof·ness noun
II. noun
Date: 1799
1. : a waterproof fabric
2. chiefly British : raincoat
III. transitive verb
Date: 1841
: to make waterproof
• wa·ter·proof·er noun