Treachery

Pronunciation: /ˈtrɛtʃəriː/

Treachery (noun)

  1. Act of being unfaithful to someone who trusted you, especially by secretly helping their enemy.
  2. Behaviour that breaks promises or loyalties in a hidden way, causing harm to others.
  3. In politics or war, the act of helping an opposing side instead of your own group.

Examples

  • His treachery broke the trust between them.
  • The team suffered treachery when a member leaked plans.