1. A fundamental or most important fact that is essential to understanding a situation, argument, or case
The cardinal fact in this murder investigation is the time of death.
O fato cardinal nesta investigação de homicídio é a hora da morte.
2. In law, a fact of primary importance that determines the outcome of a case
The judge ruled that the cardinal fact was whether the defendant was present at the scene.
O juiz decidiu que o fato cardinal era se o acusado estava presente no local.