The name Iacchus originates from the Greek Ἴακχος (Iakchos), derived from ἰάχω (iacho) meaning 'to shout'. It refers to an obscure Greek god worshipped in the Eleusinian mysteries, later identified with Dionysos. Iacchus is believed to have personified the ritual exclamation 'Iacche!' during the Eleusinian procession. His association with Dionysus likely stems from the phonetic similarity between Iacchus and Bacchus, another name for Dionysus.