noun
quisling
KWIZ-ling/ˈkwɪzlɪŋ/
A traitor who helps an enemy occupying the traitor's country.
The quisling helps the occupying army identify members of the resistance.

Etymology
Quisling's surname became a label for an enemy collaborator because he headed Norway's puppet government during the German occupation. The personal name thus became a general term for this kind of traitor.
In context
owing to his collaboration with Nazi Germany. Outside of Norway, the word “quisling” has outlasted the memory of Vidkun Quisling himself and became synonymous with “traitor,” a use that began during the war.
More examples
- Villagers call the mayor a quisling for helping the occupying troops.
- After the occupation ends, several quislings face trial for treason.
- She refuses to become a quisling by handing her neighbors over to the invaders.
Forms
quisling · quislings
Similar words
- collaborator
- Can mean an enemy helper, but also an ordinary coworker.
- traitor
- Covers betrayal generally, not just assistance to an occupying enemy.