any warm-blooded vertebrate having the skin more or less covered with hair; young are born alive except for the small subclass of monotremes and nourished with milk
"The researcher confirmed that despite its strange appearance, the newly discovered creature was indeed mammalian because it fed its live-born offspring with milk."
Any mammal.
"While studying the local wildlife, she realized that every single mammalian species in the forest relies on a complex food web to survive."
of or relating to the class Mammalia
"The fossilized skull belonged to a mammalian ancestor that lived millions of years ago."
of, or pertaining to, mammals
"The scientist confirmed that the newly discovered fossil was mammalian by examining its specialized jawbone structure."