musical vs unmusical

musical is a noun but unmusical is not a noun.

Word	Noun	Adjective	Verb	Adverb
musical	Yes	Yes	No	No
unmusical	No	Yes	No	No

musical (noun)	unmusical (noun)
a play or film whose action and dialogue is interspersed with singing and dancing

musical (adjective)	unmusical (adjective)
characteristic of or resembling or accompanied by music	not musical in nature
talented in or devoted to music	lacking interest in or talent for music
containing or constituting or characterized by pleasing melody	lacking melody
characterized by or capable of producing music