[wa.ter.proof] adj (1736): impervious to water; esp: covered or treated with a material (as a solution of rubber) to prevent permeation by water -- wa.ter.proof.ness n
[2]waterproof n (1799) 1: a waterproof fabric
2. chiefly Brit: raincoat [3]waterproof vt (1841): to make waterproof -- wa.ter.proof.er n