(1) Involving an assumption made for the sake of argument or for further study or investigation. (2) Imagined for purposes of example.
The presidential candidate refused to say what she would do if faced with a hypothetical military crisis.
Hypothetical and its parent word hypothesis comes from hypo- and the Greek verb tithenai, "to put." To hypothesize is to suppose, or to put (something) under consideration. Hypothetical applies to something that is assumed to be true so that it can serve as the basis for a line of reasoning. Thus, the theory that the dinosaurs became extinct because of a giant meteor striking the earth involves the hypothesis that such a collision would have certain effects on the earth's climate.