As a Noun: 1. Something that you say or do which is intended to deceive someone. English = deception. 2. Behaviour that is intended to make people believe something which is not true. English = deceit, duplicity. 3. The action of betraying someone. English = betrayal. As a Verb or Adjective: 1. To deliberately make someone believe something that is not true. English = deceive. 2. To do something which harms someone who thinks you support or love them, often by helping their enemies or opponents. English = betray.