An innovation divine L'origine de l'accusatif dorien Ποτειδ(α)over-tilde/Ποσειδ(α)over-tilde, attique Ποσειδ(ω)over-tilde

The oaths mentioned in half-dozen Hellenistic treaties of Doric cities (Messene, Rhodes, Cos, Eleutherna and Lyttos) attest to Pi omicron tau epsilon iota delta alpha or Pi omicron sigma epsilon iota alpha?, accusative of Doric Pi omicron tau epsilon iota delta alpha nu/Pi omicron sigma epsilon iota delta alpha nu = Attic Pi omicron sigma epsilon iota delta omega nu. In an oath of the Megarian peddler in Aristophanes' Acharnians (line 798), some manuscripts also exhibit Pi omicron tau epsilon iota delta alpha or Pi omicron tau iota delta alpha. The accusative ending -alpha cannot be accounted for either as the remains of a supposed non-thematic inflection of Poseidon's name nor as a hyper-dialectalism. Instead, Pi omicron tau epsilon iota delta alpha and Pi omicron sigma epsilon iota delta alpha share a common origin with the so-called "apocopated" accusatives Pi omicron sigma epsilon iota delta omega and A pi epsilon lambda lambda omega/A pi o lambda lambda omega. Dismissing the hypothesis that comparatives had shaped the accusative of the two theonyms, this paper suggests that the innovation was triggered by the co-occurrence of eta rho omega alpha and eta rho omega nu alpha, which belonged in two secondary inflections of eta rho omega sigma, an old stem in -ou-.