mammary Syllabification: (mam·ma·ry)Pronunciation: /ˈmamərē/Translate mammary | into Italian Definition of mammary adjective [attributive] denoting or relating to the human female breasts or the milk-secreting organs of other mammals:mammary tumor viruses noun (plural mammaries) informal a breast. Origin: late 17th century: from mamma2 + -ary1mammary in other Oxford dictionaries Definition of mammary in the British & World English dictionary