Hypothesis Hy*poth"e*sis, n.; pl. {Hypotheses}. [NL., fr. Gr. ? foundation, supposition, fr. ? to place under, ? under + ? to put. See {Hypo-}, {Thesis}.] 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. [1913 Webster]

An hypothesis being a mere supposition, there are no other limits to hypotheses than those of the human imagination. --J. S. Mill. [1913 Webster]

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}. [1913 Webster]

{Nebular hypothesis}. See under {Nebular}.

The Collaborative International Dictionary of English. 2000.