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
例句
用作名词 (n.)
Man and most other mammals are viviparous. 人和其他大多数哺乳动物都是胎生的。
Among mammals whales have the greatest mass. 哺乳动物中以鲸鱼最大。