1. noun /bɜː(ɹ)θ/
a) The process of childbearing.
He was of noble birth, but fortune had not favored him.
b) An instance of childbirth.
See Also: accident of birth, bear, birth control, birthdate, birthday, birthing, birth mother, birth pangs, birth parent, birth pill, birthplace, birthrate, birthright, birthstone, born, breech birth, give birth, noble birth, virgin birth
2. adjective /bɜː(ɹ)θ/
A familial relationship established by childbirth.
Her birth father left when she was a baby; she was raised by her mother and stepfather.
3. verb /bɜː(ɹ)θ/
Biological evolution created a human mind that enabled cultural evolution, which now outpaces and outclasses the force that birthed it.
Wikipedia foundation.