quisling
Concise Oxford English Dictionary © 2008 Oxford University Press:
quisling /ˈkwɪzlɪŋ/
▶noun a traitor collaborating with an occupying enemy force.
– origin Second World War: from the name of Major Vidkun Quisling, who ruled Norway on behalf of the German occupying forces.
'quisling' also found in these Oxford entries:

