skinny vs boney

skinny is a noun but boney is not a noun.

Word	Noun	Adjective	Verb	Adverb
skinny	Yes	Yes	No	No
boney	No	Yes	No	No

As adjectives, skinny and boney are synonyms defined as:

Other synonyms of skinny include bony, scraggly, scraggy, scrawny, underweight, weedy.

skinny (noun)	boney (noun)
confidential information about a topic or person

skinny (adjective)	boney (adjective)
of or relating to or resembling skin	having bones especially many or prominent bones
giving or spending with reluctance	being very thin
being very thin
fitting snugly