1) Alternative name for dionysus 2) Epithet of Dionysus 
In Greek mythology, Iacchus (also Iacchos, Iakchos) (Ἴακχος) is an epithet of Dionysus, particularly associated with the Mysteries at Eleusis, where he was considered to be the son of Zeus and Demeter. Iacchus was the torch bearer of the procession from Eleusis, sometimes regarded as the herald of the `divine child` of the Goddess, born i.....
minor deity associated with the Eleusinian Mysteries, the best known of the ancient Greek mystery religions. On the day preceding the commencement of ...
an archetypal Divine Child and byform of Dionysus. He carried the torch into the Eleusinian Mysteries.
In the ancient Greek Eleusinian Mysteries, the personification of the ritual cry `iakkh' o iakkhe`, regarded as a son of Zeus by Demeter. In later mythology he is identified with Dionysus. ...
Iacchus is an alternative name for Dionysus.