Origins
The word 'natal' is among the most transparent Latin borrowings in English, having preserved its original meaning of 'pertaining to birth' almost unchanged for over six centuries. It derives from Latin 'nātālis,' an adjective formed from 'nātus' (born), the past participle of 'nāscī' (to be born).
In Latin, 'diēs nātālis' meant 'birthday.' This phrase was so commonly used that 'nātālis' alone came to stand for 'birthday' in colloquial speech. When Christianity adopted December 25th as the celebration of Christ's birth, 'diēs nātālis' (or simply 'nātālis') became the standard Latin term for Christmas. This usage survives directly in Portuguese 'Natal,' Italian 'Natale,' and — through significant phonological transformation — French 'Noël' (from Old French 'Nael,' from Latin 'nātālis' with the unstressed first syllable and the intervocalic 't' lost).
The geographic name 'Natal' in South Africa was given by Portuguese explorer Vasco da Gama, who sighted the coast on Christmas Day 1497. The Brazilian city of Natal was similarly named because it was founded on December 25, 1599. These place names preserve the Latin 'birthday' meaning frozen in geography.
Literary History
In English, 'natal' entered the language in the late fourteenth century through medical and astrological writing. A person's 'natal star' or 'natal chart' in astrology referred to the configuration of celestial bodies at the moment of birth. Medical usage — 'natal complications,' 'natal care' — followed naturally.
The word's modern prominence owes much to its use in compound medical terms. 'Prenatal' (before birth) appeared in the mid-nineteenth century. 'Neonatal' (pertaining to newborn infants, from Greek 'neos' meaning 'new' plus Latin 'nātālis') emerged in the early twentieth century. 'Postnatal' (after birth) completed the trilogy. 'Perinatal' (around the time of birth) is a later addition. These compounds have made 'natal' far more familiar to modern English speakers than the standalone adjective would otherwise be.
The Latin verb 'nāscī' from which 'natal' derives is a deponent verb — passive in form but active in meaning, reflecting the ancient Roman conceptualization of birth as something that happens to you rather than something you do. This grammatical peculiarity had no effect on the English borrowings, but it offers a glimpse of how Latin speakers thought about the birth event.
Proto-Indo-European Roots
The deeper etymology connects 'natal' to the vast PIE root *ǵenh₁- (to beget), though the phonological path from *ǵenh₁- to Latin 'nāscī' requires explanation. The PIE root produced a suffixed form *ǵn̥h₁-sko- (with the inchoative suffix *-sko- indicating 'beginning to'), which in Latin became 'gnāscī' and then, with loss of the initial 'g,' 'nāscī.' The past participle 'gnātus' similarly simplified to 'nātus.' This loss of initial 'g' before 'n' was regular in Latin — compare 'nōscere' (to know) from earlier 'gnōscere,' related to Greek 'gnōsis' and English 'know.'
The word family in English is extensive: 'natal,' 'native,' 'nature,' 'nation,' 'nascent,' 'innate,' 'naïve,' 'renaissance' (literally 'rebirth'), and 'cognate' (born together, from 'co-' + 'gnātus'). All these words, despite their varied modern meanings, share the single Latin concept of being born — and behind that Latin concept lies the PIE root that also gave English its native words 'kin' and 'kind.'