Galactorrhea: The spontaneous flow of milk from the nipple at any time other than during nursing.
Galactorrhea can be due to "normal" factors such as an unrecognized pregnancy, trauma, surgery, overexercise or one of a number of drugs (including amphetamine, cimetidine, female hormone replacement therapy, hydroxyzine, methyldopa, nicotine, narcotics, reserpine, antidepressants of the so-called tricyclic type, or verapamil).
Galactorrhea can also be due to "abnormal" factors of a pathologic nature such as cirrhosis of the liver, a false pregnancy (pseudocyesis), renal (kidney) failure, disorders of the spinal cord, or a prolactinoma (a benign pituitary tumor that secretes the hormone prolactin which stimulates milk production).
The word "galactorrhea" comes from the Greek "galaktos" meaning "milk" + "rhein" meaning "to flow" = "to flow milk." (The naturally occurring sugar in breast milk is called galactose.) Galactorrhea is also sometimes called witch's milk.