riskless vs safe

riskless is not a noun while safe is a noun.

Word	Noun	Adjective	Verb	Adverb
riskless	No	Yes	No	No
safe	Yes	Yes	No	No

riskless (noun)	safe (noun)
	strongbox where valuables can be safely kept
	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

riskless (adjective)	safe (adjective)
thought to be devoid of risk	free from danger or the risk of harm
	having reached a base without being put out
	financially safe
	(of an undertaking) secure from risk