safe vs fail-safe

safe and fail-safe both are nouns.

Word	Noun	Adjective	Verb	Adverb
safe	Yes	Yes	No	No
fail-safe	Yes	Yes	No	No

safe (noun)	fail-safe (noun)
strongbox where valuables can be safely kept	a mechanism capable of returning to a safe state in case there is a failure or malfunction
contraceptive device consisting of a sheath of thin rubber or latex that is worn over the penis during intercourse
a ventilated or refrigerated cupboard for securing provisions from pests

safe (adjective)	fail-safe (adjective)
free from danger or the risk of harm	eliminating danger by compensating automatically for a failure or malfunction
having reached a base without being put out	guaranteed not to fail
financially safe
(of an undertaking) secure from risk