Mud

Mud or MUD can refer to one of several things:

Mud, a liquid or semi-liquid mixture of water and soil, or sediment, is commonly referred to as mud. Geologically speaking, mud is a mixture of water and particles of silt and clay. Ancient mud deposits harden over geological time to siltstone or mudrock (lutites).
Mud, in the construction industry, is wet plaster, joint compound, stucco, cement or other similar substance. See also slurry.
MUD, in the game of contract bridge, is a defensive signalling convention that stands for Middle-Up-Down. A defender who plays his cards in this order is better able to communicate to his partner the number of cards he holds in the suit. The partner is thus able to infer the complete distribution of the suit.
Mud bath, possibly with special ingredients, is sometimes applied for beauty, health, or pleasure.
Mud, (band), the British glam rock band formed in 1968 and best remembered for their singles Tiger Feet and Lonely This Christmas.
Multi-User Dungeon, a type of computer game
Drilling mud, used for drilling deep holes.
Mud race, term for non-whites in white supremacy.