Mammal (noun)

1. A warm-blooded vertebrate animal that has fur or hair and typically gives birth to live young, nourishing them with milk from mammary glands.
2. Animals that are characterized by the presence of mammary glands, hair, three middle ear bones and a neocortex region in the brain.

Origin:

Late 18th century: from french mammifère, from latin mammalis, from mamma "breast".

Examples:

1. Elephants are the largest land mammal.
2. Dolphins are mammals, not fish.
3. The mammal exhibit at the zoo has many different species.
4. The mammal brain is more complex than that of reptiles.
5. Mammals are warm-blooded and give birth to live young that are nourished with milk.