vera causa
/ˌveərəˈkaʊzə/noun
(pl. verae causae /ˌveəriːˈkaʊziː/)
- chiefly historical (in Newtonian philosophy) the true cause of a natural phenomenon, by an agency whose existence is independently evidenced〈主史〉（牛顿哲学用语）自然现象的真正原因。
词源
Latin, literally 'real cause'.