an infant or very young child.

an infant or very young child.

the youngest member of a family, group, etc.: I was the baby of the family for ten years, until my twin brothers were born.

an adult who behaves like a child; an immature, helpless, or fearful person: Just swallow the medicine—don't be such a baby!

a human fetus: The baby hasn’t arrived yet, but the nursery is ready.