The etymology refers to the gesture of refusal, which in Ancient Greece consists of rejecting the head backwards, therefore moving the face upwards. If taken literally, it derives the archaic verb ἀναίνομαι from a synonym ἀνανεύω, which is morphologically clearer. The segmentation would thus be ἀνα(ι)-ν-ομαι where the root of νεύω is reduced to [n]. It implies two formal manipulations which remain implicit, the insertion of a [I] and the deletion of the [eu] diphthong. However, it is more likely that it is an elliptic etymology analyzing the word as ἀνα- + αἰνέω (see ἀναίνομαι / ἀ- + αἰνέω), where only the first part is explained, the connection with αἰνέω remaining implicit. In the latter case, this is indeed the correct explanation in modern terms