What is "enion"

In the mythological writings of William Blake, Enion is an Emanation/mate of Tharmas, one of the four Zoas, who were created when Albion, the primordial man, was divided fourfold. She represents sexuality and sexual urges while Tharmas represents sensation. In her fallen aspect, she is a wailing woman that is filled with jealousy. After the Final Judgment, she is reunited with Tharmas and able to experience an idealised sexual union.