αἴθριος · aithrios — LSJ
clear, bright, clear
clear, bright, of weather, αἰθρίου ἐόντος τοῦ ἠέρος Hdt. 2.25; αἴ. πάγος clear frost, S. Fr. 149; f.l. in Ant. 357.
2 which cause a clear sky
epith. of Ζεύς, Heraclit. 120, Theoc. 4.43, cf. Arist. Mu. 401a17, Thphr. CP 5.12.2; of winds which cause a clear sky, h.Ap. 433, Arist. Mete. 364b29; esp. of the North wind, ib. 358b1.
II kept in the open air
kept in the open air, στέφη Cratin. 22.
III
αἴθριον, τό, adaptation of Lat. atrium to a Greek sense, J. AJ 3.6.2, Luc. Anach. 2, POxy. 268.22 (i A. D.), etc.