1. Food, especially semiliquid food, that is of particularly low quality or otherwise unappetizing. I'm so sick of the slop they've been serving us in the cafeteria.

2. Food or drinks that have not been completely eaten or drunk by someone; leftovers. Almost always written as "slops." We were so poor that we used to go around the bar filling our glasses with the slops left behind by other people. Having a dog is a great way to get rid of the slops when we're done eating, rather than having them go into a landfill.