1. To take for granted as being true in the absence of proof to the contrary: We presumed she was innocent.

2. To constitute reasonable evidence for assuming; appear to prove: A signed hotel bill presumes occupancy of a room.

3. To venture without authority or permission; dare: He presumed to invite himself to dinner.

1. To act overconfidently; take liberties.

2. To take unwarranted advantage of something; go beyond the proper limits: Don't presume on their hospitality.

3. To take for granted that something is true or factual; suppose: That's the new assistant, I presume.

Synonyms: These verbs signify to take something for granted or as being a fact. To presume is to suppose that something is reasonable or possible in the absence of proof to the contrary: "I presume you're tired after the long ride" (Edith Wharton).
Presuppose can mean to believe or suppose in advance: It is unrealistic to presuppose a sophisticated knowledge of harmony in a beginning music student.
Postulate and posit denote the assertion of the existence, reality, necessity, or truth of something as the basis for reasoning or argument: "We can see individuals, but we can't see providence; we have to postulate it" (Aldous Huxley).
To assume is to accept something as existing or being true without proof or on inconclusive grounds: "We must never assume that which is incapable of proof" (G.H. Lewes).