backstabber
noun/ˈbækˌstæbɚ/
Etymology From back + stabber.
1
A traitor or hypocrite, such as a co-worker or friend assumed trustworthy but who figuratively attacks when one's back is turned.
- Related terms
- stab in the back
Entry derived from the Wiktionary, under licence CC BY-SA 4.0 — list of authors.