Freebooter is a noun that refers to a pirate or adventurer. 

Derived from a word that combines the Dutch word for ‘free’ and ‘booty,’ our word of the day was first used in reference to Dutch privateers who operated in the Caribbean to plunder Spanish ships. In time the word came to refer to anyone in the habit of taking free booty, or goods. Here’s an example:

Those bagels Margie brought into the office looked awfully tasty, but I had to resist. I’m afraid that after my unfortunate habit of chowing down on free food, I’ve gained a reputation as a freebooter.