HAG, a word common during the 16th and 17th centuries for a female demon or evil spirit, and so particularly applied to harpies and fairies of classical mythology, and also to witches. (Ger. Hexe, fr. O.E. haegtesse.) The name is also used of an eel-like parasitic fish, Myxine, allied to the lamprey; of a kind of light said to appear at night ; of a copse (north England and Scotland), and of a cutting in the peat of a bog.