WordNet sense 1 (the lofty nest of a bird of prey (such as a hawk or eagle)):

aerie, eyrie, eyry

WordNet sense 2 (characterized by lightness and insubstantiality; as impalpable or intangible as air):

aerial, airy, ethereal, aeriform, aerial

WordNet sense 3 (lacking material form or substance; unreal):

insubstantial, unreal, unsubstantial