formal vs ceremonious

formal is a noun but ceremonious is not a noun.

Word	Noun	Adjective	Verb	Adverb
formal	Yes	Yes	No	No
ceremonious	No	Yes	No	No

formal (noun)	ceremonious (noun)
a gown for evening wear
a lavish dance requiring formal attire

formal (adjective)	ceremonious (adjective)
being in accord with established forms and conventions and requirements (as e.g. of formal dress)	characterized by pomp and ceremony and stately display
(of spoken and written language) adhering to traditional standards of correctness and without casual, contracted, and colloquial forms	rigidly formal or bound by convention
refined or imposing in manner or appearance; befitting a royal court
logically deductive
represented in simplified or symbolic form
characteristic of or befitting a person in authority