The Collaborative International Dictionary of English v.0.48:

mammary gland \mammary gland\ n.
   The milk-secreting organ of female mammals.

   Syn: mamma.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

mammary gland
    n 1: milk-secreting organ of female mammals [syn: mammary
         gland, mamma]

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "mammary gland":
   bag, boobs, bosom, breast, breasts, brisket, bust, chest, crop,
   dug, knockers, mama, mamelon, mamelonation, mammilla, mammillation,
   nenes, nipple, pap, papilla, pigeon breast, teat, thorax, tit,
   tits, titties, titty, udder