rainproof

adjective

1. impervious to rain; keeping out or unaffected by rain: a rainproof cover; a rainproof coat.

verb (used with object)

2. to make rainproof.

adjective

1. Also: raintight (of garments, materials, buildings, etc) impermeable to rainwater

verb

2. (tr) to make rainproof

adj.

also rain-proof, 1788, from rain (n.) + proof (n.).