Hy*poth"e*sis (?), n.; pl. Hypotheses (#). [NL., fr. Gr. foundation, supposition, fr. to place under, under + to put. See Hypo-, Thesis.]
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.
An hypothesis being a mere supposition, there are no other limits to hypotheses than those of the human imagination.
J. S. Mill.
2. Natural Science
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.
Syn. -- Supposition; assumption. See Theory.
Nebular hypothesis. See under Nebular.
© Webster 1913.