vernacular vs airhead

vernacular and airhead both are nouns.

Word	Noun	Adjective	Verb	Adverb
vernacular	Yes	Yes	No	No
airhead	Yes	No	No	No

vernacular (noun)	airhead (noun)
the everyday speech of the people (as distinguished from literary language)	a bridgehead seized by airborne troops
a characteristic language of a particular group (as among thieves)	a flighty scatterbrained simpleton

vernacular (adjective)	airhead (adjective)
being or characteristic of or appropriate to everyday language