The phrase out of wedlock refers to someone who was born to unmarried parents, but what is wedlock? The term simply means "marriage", but is so archaic that many people now think that it refers to when women get pregnant outside of marriage, due to association with the much more frequent phrase. In Middle English, the word was spelled wedlok or wedlocke and traces to Old English wedlac, still with the same definition. This has nothing to do with locks (it was folk etymologized); it's composed of the word wed that we know and the suffix -lac, a noun denoting actions that traces to the Proto-Indo-European reconstruction leyg, meaning "bounce". Wed, through Proto-Germanic wadja, ultimately derives from a Proto-Indo-European word for "bind", with a similar pronunciation.
Hello! I'm Adam Aleksic. This year, I graduated from Harvard University with a degree in Government and Linguistics. There, I co-founded the Harvard Undergraduate Linguistics Society and wrote a thesis on Serbo-Croatian language policy, magna cum laude. In addition to etymology, I also really enjoy philosophy, trivia, vexillology, geography, board games, conlanging, art history, and law.