Pronunciation : Hy*poth"e*sis Part of Speech : n.; Etymology : [NL., fr. Gr. Hypo-, Thesis.] Definition : 1. 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)
Defn: 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.
pl. Hypotheses. Source : Webster's Unabridged Dictionary, 1913