—v.t. 1. to assume (something), as for the sake of argument or as part of a proposition or theory: Suppose the distance to be one mile. 2. to consider (something) as a possibility suggested or an idea or plan proposed: Suppose we wait until tomorrow. 3. to believe or assume as true; take for granted: It is supposed that his death was an accident. 4. to think or hold as an opinion: What do you suppose he will do? 5. to require logically; imply; presuppose: The evidence supposes his presence near the scene. 6. (used in the passive) to expect or design; require or permit (fol. by an infinitive verb): The machine is supposed to make noise. I'm not supposed to run fast.