one full year after birth; specifically refers to a child's first birthday or the celebration held on that day

(colloquial) The celebration of a child's first birthday; refers to the custom of celebrating when a baby reaches one year of age.

a celebration or party given for a baby who has reached the age of one hundred days

A custom performed on a baby's first birthday to predict their future career or personality by placing various objects in front of them and seeing which one they grab first.