Is it suppose, supposed, or supposed to? Learn the difference between 'suppose' vs 'supposed', how and when to use each of them, and how to... Suppose definition: To assume to be true or real for the sake of argument or explanation. Suppose definition: to assume (something) for the sake of argument, as part of a proposition or theory, a problem set to be solved as an exercise, etc... See examples of SUPPOSE used in a sentence. Definition of suppose verb in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.