An animal of the class Mammalia, characterized by being warm-blooded, having hair and producing milk with which to feed its young.
"The biologist confirmed that despite its small size and unique pouch, the marsupial is indeed a mammal because it nurses its joey with milk."
The word "mammal" comes from the Modern Latin term Mammalia, which was coined in 1758 by Linnaeus. It is derived from the Latin word mamma, meaning "breast."