-proof
1.
a combining form meaning “resistant, impervious to” that specified by the initial element:
burglarproof; childproof; waterproof.
British Dictionary definitions for
-proof
-proof
adjective, combining form
1.
secure against (damage by); (make) impervious to:
waterproof,
mothproof,
childproof
Word Origin
from
proof
(adj)