I occasionally have a pirate in my house–this is to be expected when one has a 7-year-old boy. I never quite know when a rather adorable little figure is going to appear with his sword in hand and demand all my booty. But last time he did, his sister–being so very much my daughter–asked, laughing, “Where does that come from, anyway? Did they put treasure in a boot or something?”
As it happens…no. 😉 Booty is from the Old French butin, which is turn from the Germanic bute, which means “exchange.” So booty is quite literally something gotten in exchange for something else (in the pirate’s case, they got it in exchange for a fight, I suppose…) But in Old English we also had the word bot that meant “an improvement,” which had, by the time butin came into our vernacular, become boot. So we combined the two into booty, making it something profitable.
The noun that means “a woman’s posterior” is from the 1920.