Lactating describes a mammal that produces milk to feed her babies. A lactating mother cat might nurse as many as six or seven kittens at once!
Most lactating animals have recently given birth, and their bodies are now prepared to provide their young with milk. There are lactating human mothers, lactating cows that are milked instead of feeding their calves, and lactating dogs with litters of puppies. The thing they all have in common is being mammals. The words lactating, lactate, and lactation stem from the Latin lactationem, "a suckling," from a root word that means "milk."