Look up half-birthday in Wiktionary, the free dictionary.
A half-birthday is a day approximately six months before or after the anniversary of a person's birth. It is sometimes marked by people whose birthday either falls on major holidays, near major holidays, or both, the celebration of which may overshadow celebration of the birthday.[1] It may also be marked by students whose birthday does not occur during the regular school year; a half-birthday allows a celebration with friends at school, with half a cake.[2]