safety lock

English Thesaurus

1. a bolt that cannot be moved from outside the door or gate (noun.artifact)

hypernym	:	bolt, deadbolt,
definition	:	the part of a lock that is engaged or withdrawn with a key (noun.artifact)

2. guard consisting of a locking device that prevents a weapon from being fired (noun.artifact)

hypernym	:	guard, safety, safety device,
definition	:	a device designed to prevent injury or accidents (noun.artifact)

part meronym	:	gun,
definition	:	a weapon that discharges a missile at high velocity (especially from a metal tube or barrel) (noun.artifact)