G0109
ἀήρ
air
ἀήρ, ἀέρος, ὁ, [in LXX: 2Ki.22:12 (= Psa.17(18):11 שׁחק), Wi .8 ;] in Hom., Hes., the lower air which surrounds the earth, as opposite to the purer αἰθήρ of the higher regions; generally, air (MM, VGT, see word): Act.22:23, 1Th.4:17, Rev.9:2 16:17; of the air as the realm of demons, Eph.2:2; ἀ. δέρειν, of striving to no purpose, 1Co.9:26; εἰς ἀ. λαλεῖν, of speaking without effect, not being understood, 1Co.14:9.† (AS)
Full Thayer's lexicon entry
ἀήρ — aḗr
ἀήρ, ἀέρος, ὁ (ἄημι, ἄω (cf. ἄνεμος, at the beginning)), the air (particularly the lower and denser, as distinguished from the higher and rarer ὁ αἰθήρ, cf. Homer, Iliad 14, 288), the atmospheric region: Act 22:23; 1Th 4:17; Rev 9:2; Rev 16:17; ὁ ἄρχων τῆς ἐξουσίας τοῦ ἀέρος in Eph 2:2 signifies 'the ruler of the powers (spirits, see ἐξουσία 4 c. ββ.) in the air,' i. e. the devil, the prince of the demons that according to Jewish opinion fill the realm of air (cf. Meyer at the passage; (B. D. American edition under the word; Stuart in Bib. Sacr. for 1843, p. 139f)). Sometimes indeed, ἀήρ denotes a hazy, obscure atmosphere (Homer, Iliad 17, 644; 3, 381; 5, 356, etc.; Polybius 18, 3, 7), but is nowhere quite equiv, to σκότος — the sense which many injudiciously assign it in Ephesians, the passage cited ἀέρα δέρειν, (cf.verberat ictibus auras, Vergil Aen. 5, 377, of pugilists who miss their aim) i. e. to contend in vain, 1Co 9:26; εἰς ἀέρα λαλεῖν (verba ventis profundere, Lucr. 4, 929 (932)) 'to speak into the air' i. e. without effect, used of those who speak what is not understood by the hearers, 1Co 14:9.
7 occurrences
Acts (1), I Corinthians (2), Ephesians (1), I Thessalonians (1), Revelation of John (2)