The Collaborative International Dictionary of English v.0.48:
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
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. Hypothetic