1.a statement that is assumed to be true and from which a conclusion can be drawn;
on the assumption that he has been injured we can infer that he will not to play
2.a hypothesis that is taken for granted;
any society is built upon certain assumptions
3.the act of taking possession of or power over something;
his assumption of office coincided with the trouble in Cuba
4.audacious (even arrogant) behavior that you have no right to;
he despised them for their presumptuousness
5.the act of assuming or taking for granted;
your assumption that I would agree was unwarranted