This etymology is rather simple, deriving the word from a rare verb through only one formal manipulation, the addition of a consonant. This addition was very easy at a time when the [g] was already pronounced [j] before a front vowel, so that it implies probably a prononciation [avji] as in Modern Greek. This prononciation is already attested sporadically in Ptolemaic papyri and was probably generalized by the 4th c. AD. From the semantic point of view, deriving a word for "light" from a verb meaning "to shine" is straightforward, this is a descriptive etymology.

A variant is found in the Etym. Gudianum Additamenta, alpha p. 230 (Αὐγή· ἀπὸ τοῦ ἄω, τοῦ σημαίνοντος τὸ φαίνω, ἀγή, καὶ πλεονασμῷ τοῦ υ αὐγή), from a verb *ἄω "to bring to light" which is not attested and is an ad hoc construction of etymologists