counterfactualPronunciation: /ˌkaʊntəˈfaktʃʊəl, -tjʊəl/ PhilosophyDefinition of counterfactual adjective relating to or expressing what has not happened or is not the case. noun a counterfactual conditional statement (e.g. If kangaroos had no tails, they would topple over). counterfactual in other Oxford dictionaries Definition of counterfactual in the US English dictionary