depression vs air mass

depression and air mass both are nouns.

Word	Noun	Adjective	Verb	Adverb
depression	Yes	No	No	No
air mass	Yes	No	No	No

As nouns, air mass is a hypernym of depression; that is, air mass is a word with a broader meaning than depression:

depression (noun)	air mass (noun)
pushing down	a large body of air with uniform characteristics horizontally
sad feelings of gloom and inadequacy
a sunken or depressed geological formation
angular distance below the horizon (especially of a celestial object)
a concavity in a surface produced by pressing
a mental state characterized by a pessimistic sense of inadequacy and a despondent lack of activity
an air mass of lower pressure; often brings precipitation
a long-term economic state characterized by unemployment and low prices and low levels of trade and investment
a state of depression and anhedonia so severe as to require clinical intervention