Emily Dickinson Lexicon

MAM'MI-FER, n. [L. mamma, the breast, and fero, to bear.]

An animal which has breasts for nourishing its young. The mammifers have a double system of circulation, red and warm blood; the fetus is nourished in the matrix by means of one or more placentas, and the young by milk secreted by the breasts. Dict. Nat. Hist.