Mud is very wet dirt. On rainy days, you might enjoy putting on your tall rubber boots and squishing around in the mud.
When you mix soil with water, you get mud — a soft, almost sticky material. Mud results from a damp environment or a recent rain. There's also the mud that masons or bricklayers use to stick stones together — it resembles mud, though it's actually mortar or plaster, and to use it when building is to mud. The word mud also showed up in 1920s as slang" meaning "bad coffee," and if your "name is mud," you've got a bad reputation.