The word peculiar has quite a peculiar etymology! The Oxford English Dictionary shows it as first cropping up in the middle of the fifteenth century, and etymologists have concluded that it was borrowed directly from Latin peculiaris, which meant "one's own property". The current definition of "unusual" arose because peculiar things were considered to be special attributes of a specific person or thing, just like property is owned by a particular person. Peculiaris comes from the noun peculium, which meant "private property" but more literally could be interpreted as "property in cattle", because a lot of wealth was measured in livestock back then. The root is pecus, or "cattle", and that, through an earlier form sounding like peku, derives from Proto-Indo-European peku, with the same meaning.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.