criminal vs felonious

criminal is a noun but felonious is not a noun.

Word	Noun	Adjective	Verb	Adverb
criminal	Yes	Yes	No	No
felonious	No	Yes	No	No

As adjectives, criminal and felonious are synonyms defined as:

criminal and felonious: involving or being or having the nature of a crime

criminal (noun)	felonious (noun)
someone who has committed a crime or has been legally convicted of a crime

criminal (adjective)	felonious (adjective)
guilty of crime or serious offense	involving or being or having the nature of a crime
involving or being or having the nature of a crime
bringing or deserving severe rebuke or censure