bird's nest vs aery

bird's nest and aery both are nouns.

Word	Noun	Adjective	Verb	Adverb
bird's nest	Yes	No	No	No
aery	Yes	Yes	No	No

As nouns, aery is a hyponym of bird's nest; that is, aery is a word with a more specific, narrower meaning than bird's nest:

Other hyponyms of bird's nest include aerie, eyrie, eyry.

bird's nest (noun)	aery (noun)
nest where birds lay their eggs and hatch their young	any habitation at a high altitude
	the lofty nest of a bird of prey (such as a hawk or eagle)

bird's nest (adjective)	aery (adjective)
	characterized by lightness and insubstantiality; as impalpable or intangible as air