suffix
[in adjectives]
used to describe something which a particular thing cannot harm or pass through, or which protects people against that thing
　a bulletproof car
　a waterproof jacket
　an ovenproof dish (=that cannot be harmed by heat)
[in adjectives]
used to describe something which cannot easily be affected or damaged by someone or something
　a childproof container
　vandal-proof
[in verbs]
to treat or make something so that a particular thing cannot harm it or pass through it, or so that it gives protection against it
　soundproof a room (=so that sound cannot get into or out of it)