Pronunciation: (mam'u),[key] —n., —pl.mam•maePronunciation: (mam'ē)[key]for 1;mam•mafor 2. 1. Anat.,Zool.a structure, characteristic of mammals, that comprises one or more mammary glands with an associated nipple or teat, usually rudimentary unless developed and activated for the secretion of milk in the female after the birth of young.
2. Meteorol.(used with a pl. v.) hanging, breastlike protuberances on the under surface of a cloud.