counterfactual - definition and synonyms

noun [countable]  /ˌkaʊntə(r)ˈfæktʃuəl/
singularcounterfactual
pluralcounterfactuals
  1. a description or examination of what might have happened if events had been different

    Few things stimulate the imagination like a good counterfactual. What if that attempt on Hitler's life had succeeded? What if John Kennedy had lived?