Derivational etymology requiring one formal change, which relies on the existing interchanges between /r/ and /l/ correctly identified by Greek grammarians (and linguistically resulting from the dissimilation of liquid consonants). Semantically, the etymology was easy because ἐλαύνω, here under the form ἐλάω, means "to drive" but also "to propel a ship, to row" (νῆα ἐλάαν Od. 12.109), and the compound κωπηλάτης, lit. "oar-driver", means "rower". Therefore, the assumed etymon is the verb from which the lemma is the agent noun. This is a reformulation of Philoxenus' etymology (see ἐρέτης / ἐρέσσω): Philoxenu's derivation is ἐλαύνω → *ἐλέσσω → ἐρέσσω → ἐρέτης. Therefore, in Philoxenus' opinion the immediate etymon of ἐρέτης is ἐρέσσω, and ἐλαύνω is the etymon of the etymon. However, in later works, the etymon of the etymon is assumed as the direct etymon of the lemma.