quag
Concise Oxford English Dictionary © 2008 Oxford University Press:
quag /kwag, kwɒg/
▶noun archaic a marshy or boggy place.
– derivatives
quaggy adjective.
quaggy adjective.
– origin C16: rel. to dial. quag ‘shake’; prob. symbolic, the qu- suggesting movement (as in quake).
'quag' also found in these Oxford entries:

