Bona Dea, the “good goddess,” an old Roman deity of fruitfulness, both in the earth and in women. She was identified with Fauna, and by later syncretism also with Ops and Maia—the latter no doubt because the dedication-day of her temple on the Aventine was 1st May (Ovid, Fasti, v. 149 foll.). This temple was cared for, and the cult attended, by women only, and the same was the case at a second celebration at the beginning of December in the house of a magistrate with imperium, which became famous owing to the profanation of these mysteries by P. Clodius in 62 B.C., and the political consequences of his act. Wine and myrtle were tabooed in the cult of this deity, and myths grew up to explain these features of the cult, of which an account may be read in W.W. Fowler’s Roman Festivals, pp. 103 foll. Herbs with healing properties were kept in her temple, and also snakes, the usual symbol of the medicinal art. Her victim was a porca, as in the cults of other deities of fertility, and was called damium, and we are told that the goddess herself was known as Damia and her priestess as damiatrix. These names are almost certainly Greek; Damia is found worshipped at several places in Greece, and also at Tarentum, where there was a festival called Dameia. It is thus highly probable that on the cult of the original Roman goddess was engrafted the Greek one of Damia, perhaps after the conquest of Tarentum (272 B.C.). It is no longer possible to distinguish clearly the Greek and Roman elements in this curious cult, though it is itself quite intelligible as that of an Earth-goddess with mysteries attached.
See also Pauly-Wissowa, Realencyclopadie.