donnish vs academic

donnish is not a noun while academic is a noun.

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

As adjectives, donnish and academic are synonyms defined as:

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

Other synonyms of donnish include pedantic.

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

donnish (adjective)	academic (adjective)
marked by a narrow focus on or display of learning especially its trivial aspects	associated with academia or an academy
	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