Definition of "Baby" :

noun: a project of personal concern to someone

"This project is his baby."

noun: a very young mammal

"Baby rabbits."

noun: the youngest member of a group (not necessarily young)

"The baby of the family."

noun: a very young child (birth to 1 year) who has not yet begun to walk or talk

"The baby began to cry again."

noun: an unborn child; a human fetus

"I felt healthy and very feminine carrying the baby."

noun: an immature childish person

"Stop being a baby!."

verb: treat with excessive indulgence