A very young child, especially one newly or recently born. The baby was sleeping peacefully in the crib.
An immature or childish person. Stop being such a baby and face your fears.
A term of endearment for a loved one or partner. He called her 'baby' as they walked hand in hand.
A project or undertaking that is one's special responsibility or interest. The new marketing campaign is her baby, and she is very proud of it.
A very young animal, especially a mammal. The safari guide pointed out a baby elephant following its mother.
The youngest member of a family or group. Although he's twenty, he's still the baby of the family.