The Collaborative International Dictionary of English v.0.48:
Quag \Quag\, n. A quagmire. [R.] "Crooked or straight, through quags or thorny dells." --Cowper. [1913 Webster]WordNet (r) 3.0 (2006):
quag n 1: a soft wet area of low-lying land that sinks underfoot [syn: mire, quagmire, quag, morass, slack]