- The fact or condition of having more than two mammae or nipples.
1976, Kyril Bonfiglioli, Something Nasty in the Woodshed, Penguin, published 2001, page 420:
- The warts on its skin, you see, remind one of the extra nipples which every she-witch was supposed to have and that goes back (am I boring you, dear boy? How is your glass?) that goes back to the polymastia or superfluity of breasts of the ancients.