Derivational etymology at first sight mismatched. In fact it is a complementary etymology meant to account for one specific meaning of κέρας, used in the Septuagint as a synonym of "power, glory". This specific contextual meaning had therefore to be provided with an etymology. Grammarians did so after the model of γέρας "honour, prize of honour", which was etymologized as derived from ἐράω (see γέρας / ἐράω). Choeroboscus' formulation mentions the latter (παρὰ τὸ ἐρῶ τὸ ἐπιθυμῶ, ἔρας καὶ γέρας) without saying explicitly that it is the model after which this κέρας "glory" is explained. Formally, it requires one manipulation, the addition of a consonant, /g/ or /k/, at the beginning of the word.