A supposition; a proposition or principle which is supposed or taken for granted, in order to draw a conclusion or inference for proof of the point in question; something not proved, but assumed for the purpose of argument, or to account for a fact or an occurrence; as, the hypothesis that head winds detain an overdue steamer.

A tentative theory or supposition provisionally adopted to explain certain facts, and to guide in the investigation of others; hence, frequently called a working hypothesis.

idea being tested by experimenting.

A prediction which needs to be tested to tell if it is correct. An engineer can offer the hypothesis that a particular wing shape will not create enough lift to enable an airplane to fly. His or her hypothesis must then be tested using one or more of the Tools of Aeronautics to determine if it is correct.