RAINPROOF

rainproof, waterproof, waterproofed

(adjective) not permitting the passage of water

Source: WordNet® 3.1

Etymology

Adjective

rainproof (comparative more rainproof, superlative most rainproof)

(of external clothing) waterproof

Verb

rainproof (third-person singular simple present rainproofs, present participle rainproofing, simple past and past participle rainproofed)

To make rainproof.

Source: Wiktionary