waterproof
/ˈwɑːtɚˌpruːf/
adjective
designed to prevent water from entering or passing through
designed so that water alone will not remove it
noun
plural -proofs
[count] chiefly Brit :raincoat
verb
-proofs; -proofed; -proofing
[+ obj] :to put a substance on (something) in order to make it waterproof
US