Synonyms for Indisputable (same or very similar meaning)
WordNet sense 1 (not open to question; obviously true):
incontestable, undisputableWordNet sense 2 (not possible to deny):
undeniableWordNet sense 3 (impossible to doubt or dispute):
sureWordNet sense 4 (established beyond doubt or question; definitely known):
certainFrom the ODE community, based on WordNetadd/edit