riot vs riotous

riot is a noun but riotous is not a noun.

Word	Noun	Adjective	Verb	Adverb
riot	Yes	No	Yes	No
riotous	No	Yes	No	No

riot (noun)	riotous (noun)
a public act of violence by an unruly mob
a wild gathering involving excessive drinking and promiscuity
a joke that seems extremely funny
a state of disorder involving group violence

riot (adjective)	riotous (adjective)
	produced or growing in extreme abundance
	unrestrained by convention or morality
	characterized by unrest or disorder or insubordination

riot (verb)	riotous (verb)
take part in a riot; disturb the public peace by engaging in a riot
engage in boisterous, drunken merrymaking