Mud and Quag

Mud noun - Water soaked soil; soft wet earth.

Quag and mud are semantically related In some cases you can use "Quag" instead a noun "Mud".

Quag noun - A soft wet area of low-lying land that sinks underfoot.

Mud and quag are semantically related in swamp topic. Sometimes you can use "Mud" instead a noun "Quag".