Entry 1 sense Webster, 1913 Mammary /măm'-ẽr-ē/ · Mam·ma·ry · IPA /ˈmæməɹi/ 01 a. Of or pertaining to the mammae or breasts; as, the mammary arteries and veins. 1. Of or pertaining to the mammae or breasts; as, the mammary arteries and veins.(Anat.)