Swill is liquid food waste or garbage, often mixed together into a sloppy, unappetizing mess. Farmers traditionally fed swill to pigs: a mixture of kitchen scraps, spoiled vegetables, leftover grain, and water all stirred together in a bucket. While it looks disgusting to us, pigs don't mind eating it.

The word captures something truly gross and unappealing. If someone calls a drink “swill,” they mean it tastes terrible, like dishwater or spoiled juice. A kid might push away a cafeteria smoothie and call it swill if it's watery, flavorless, and full of mysterious lumps.

You might also hear swill used as a verb meaning to drink something quickly and messily, or to rinse or wash something out. A farmer might swill out a bucket with water, splashing it around to clean it.

The word often appears in expressions like “pig swill,” emphasizing just how unpleasant something is. When you read about characters in old novels drinking swill in a dirty tavern, the author wants you to picture something barely drinkable.