burd (n.)

c. 1200, "fact of being born;" mid-13c., "act of giving birth, a bringing forth by the mother, childbirth," sometimes in Middle English also "conception;" also "that which is born, offspring, child;" from a Scandinavian source such as Old Norse *byrðr (replacing cognate Old English gebyrd "birth, descent, race; offspring; nature; fate"), from Proto-Germanic *gaburthis (source also of Old Frisian berd, Old Saxon giburd, Dutch geboorte, Old High German giburt, German geburt, Gothic gabaurþs), from PIE *bhrto past participle of root *bher- (1) "to carry; to bear children" (compare bear (v.)).

The Germanic suffix -th is for "process" (as in bath, death). The meaning "condition into which a person is born, lineage, descent" is attested from c. 1200 (it was also in the Old English word). In reference to non-living things, "any coming into existence" is from 1610s. Birth control is from 1914; birth certificate is from 1842.

"woman newly married or about to be," Old English bryd "bride, betrothed or newly married woman," from Proto-Germanic *bruthiz "woman being married" (source also of Old Frisian breid, Dutch bruid, Old High German brut, German Braut "bride"), a word of uncertain origin.

Gothic cognate bruþs, however, meant "daughter-in-law," and the form of the word borrowed from Old High German into Medieval Latin (bruta) and Old French (bruy) had only this sense. In ancient Indo-European custom, the married woman went to live with her husband's family, thus the sole "newly wed female" in such a household would have been the daughter-in-law. On the same notion, some trace the word itself to the PIE verbal root *bhreu-, which forms words for cooking and brewing, as this likely was the daughter-in-law's job. An Old Frisian word for "bride" was fletieve, literally "house-gift."

"maiden, young girl; woman of noble birth, damsel, lady, lady in waiting," also "the Virgin Mary," c. 1200, perhaps a variant of birth (n.) "birth, lineage," confused with burd and bride (q.q.v.), but felt by later writers as a figurative use of bird (n.1), which originally meant "young bird" and sometimes in Middle English was extended to the young of other animals and humans.

In later Middle English and after, bird (n.2) largely was confined to alliterative poetry and to alliterative phrases. The modern slang meaning "young woman" is from 1915, and probably arose independently of the older word (compare slang use of chick).