Is it farther or further?
1826, anglicized form of Modern Latin Mammalia (1773), coined 1758 by Linnaeus for the class of mammals, from neuter plural of Late Latin mammalis "of the breast," from Latin mamma "breast," perhaps cognate with mamma.
Any of various warm-blooded vertebrate animals of the class Mammalia, whose young feed on milk that is produced by the mother's mammary glands. Unlike other vertebrates, mammals have a diaphragm that separates the heart and lungs from the other internal organs, red blood cells that lack a nucleus, and usually hair or fur. All mammals but the monotremes bear live young. Mammals include rodents, cats, dogs, ungulates, cetaceans, and apes.