Source : Webster's Revised Unabridged Dictionary (1913)

Suppose \Sup*pose"\, v. t. [imp. & p. p. {Supposed}; p. pr. &
   vb. n. {Supposing}.] [F. supposer; pref. sub- under + poser
   to place; -- corresponding in meaning to L. supponere,
   suppositum, to put under, to substitute, falsify,
   counterfeit. See {Pose}.]
   1. To represent to one's self, or state to another, not as
      true or real, but as if so, and with a view to some
      consequence or application which the reality would involve
      or admit of; to imagine or admit to exist, for the sake of
      argument or illustration; to assume to be true; as, let us
      suppose the earth to be the center of the system, what
      would be the result?

            Suppose they take offence without a cause. --Shak.

            When we have as great assurance that a thing is, as
            we could possibly, supposing it were, we ought not
            to make any doubt of its existence.   --Tillotson.

   2. To imagine; to believe; to receive as true.

            How easy is a bush supposed a bear!   --Shak.

            Let not my lord suppose that they have slain all the
            young men, the king's sons; for Amnon only is dead.
                                                  --2 Sam. xiii.
                                                  32.

   3. To require to exist or to be true; to imply by the laws of
      thought or of nature; as, purpose supposes foresight.

            One falsehood always supposes another, and renders
            all you can say suspected.            --Female
                                                  Quixote.

   4. To put by fraud in the place of another. [Obs.]

   Syn: To imagine; believe; conclude; judge; consider; view;
        regard; conjecture; assume.

Suppose \Sup*pose"\, v. i.
   To make supposition; to think; to be of opinion. --Acts ii.
   15.

Suppose \Sup*pose"\, n.
   Supposition. [Obs.] --Shak. ``A base suppose that he is
   honest.'' --Dryden.

Source : WordNet®

suppose
     v 1: express a supposition; "Let us say that he did not tell the
          truth"; "Let's say you had a lot of money--what would
          you do?" [syn: {say}]
     2: expect, believe, or suppose; "I imagine she earned a lot of
        money with her new novel"; "I thought to find her in a bad
        state"; "he didn't think to find her in the kitchen"; "I
        guess she is angry at me for standing her up" [syn: {think},
         {opine}, {imagine}, {reckon}, {guess}]
     3: to believe especially on uncertain or tentative grounds;
        "Scientists supposed that large dinosaurs lived in swamps"
        [syn: {speculate}, {theorize}, {theorise}, {conjecture}, {hypothesize},
         {hypothesise}, {hypothecate}]
     4: take for granted or as a given; suppose beforehand; "I
        presuppose that you have done your work" [syn: {presuppose}]
     5: require as a necessary antecedent or precondition; "This
        step presupposes two prior ones" [syn: {presuppose}]