Mammary gland: One of the two half-moon-shaped glands on either side of the adult female chest, which with fatty tissue and the nipple make up the breast. Within each mammary gland is a network of sacs that produce milk during lactation and send it to the nipple via a system of ducts.
Undeveloped mammary glands are present in female children and in males.
See also Breast, Lactation.
