academic vs donnish

academic is a noun but donnish is not a noun.

Word	Noun	Adjective	Verb	Adverb
academic	Yes	Yes	No	No
donnish	No	Yes	No	No

As adjectives, academic and donnish are synonyms defined as:

academic and donnish: marked by a narrow focus on or display of learning especially its trivial aspects

Other synonyms of academic include pedantic.

academic (noun)	donnish (noun)
an educator who works at a college or university

academic (adjective)	donnish (adjective)
associated with academia or an academy	marked by a narrow focus on or display of learning especially its trivial aspects
marked by a narrow focus on or display of learning especially its trivial aspects
hypothetical or theoretical and not expected to produce an immediate or practical result