The word paradox was borrowed by Thomas More in 1533 from the Middle French word paradoxe, which was borrowed at some point in the fourteenth century from Latin paradoxum, which still had the same definition. Paradoxum comes from Ancient Greek paradoxon, meaning "unexpected" or "incredible". More literally, it meant "contrary to opinion", as it was composed of the prefix para-, meaning "contrary" or "beyond", and the root doxa, meaning "expectation" or "opinion". Earlier on, para meant "alongside"; this is the same usage as in parallel, because the Greeks considered two viewpoints that never intersected contradictory (and, ultimately, it's from Proto-Indo-European per, "forward"). Doxa, meanwhile, derives from the Proto-Indo-European reconstruction dek, meaning "take".
Hello! I'm Adam Aleksic, a sophomore studying government and linguistics at Harvard University, where I co-founded the Harvard Undergraduate Linguistics Society. In addition to etymology, I also really enjoy politics, vexillology, geography, board games, conlanging, and law.