rash vs foolhardy

rash is a noun but foolhardy is not a noun.

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

As adjectives, rash and foolhardy are synonyms defined as:

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

Other synonyms of rash include heady, reckless.

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

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