Definition of Lycanthropy--Marcellus Sidetes--Virgil--Herodotus--Ovid--Pliny--Agriopas--Story from Petronius--Arcadian Legends--Explanation offered. WHAT is Lycanthropy? The change of manor woman into the form of a wolf, either through magical means, so as to enable him or her to gratify the taste for human flesh, or through judgment of the gods in punishment for some great offence.