foolhardy vs rash

foolhardy is not a noun while rash is a noun.

Word	Noun	Adjective	Verb	Adverb
foolhardy	No	Yes	No	No
rash	Yes	Yes	No	No

As adjectives, foolhardy and rash are synonyms defined as:

foolhardy and rash: marked by defiant disregard for danger or consequences

Other synonyms of foolhardy include heady, reckless.

foolhardy (noun)	rash (noun)
	a series of unexpected and unpleasant occurrences
	any red eruption of the skin

foolhardy (adjective)	rash (adjective)
marked by defiant disregard for danger or consequences	marked by defiant disregard for danger or consequences
	imprudently incurring risk