v. & n.
v.tr. 1 (often foll. by that + clause) assume as a necessary condition, esp. as a basis for reasoning; take for granted. 2 claim. 3 (in ecclesiastical law) nominate or elect to a higher rank.
n. 1 a thing postulated. 2 a fundamental prerequisite or condition. 3 Math. an assumption used as a basis for mathematical reasoning. postulation n.
[ L postulare postulat- demand ]