Как по Английски будет млекопитающие

noun

(in form mammalia; with plural or singular agreement) the large class of vertebrate animals comprising the mammals; (with plural agreement, also mammalia) vertebrates of this class (collectively or individually), mammals.

adjective

Containing mammalian fossil remains.

noun

A warm-blooded vertebrate animal of a class that is distinguished by the possession of hair or fur, females that secrete milk for the nourishment of the young, and (typically) the birth of live young.

Примеры использования:

It provides the growing young with everything it wants, and only mammals produce milk.