Hypothesis

n.	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) 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. Nebular hypothesis See under Nebular.

Noun	1.	hypothesis - a proposal intended to explain certain facts or observations
	2.	hypothesis - a tentative theory about the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena; "a scientific hypothesis that survives experimental testing becomes a scientific theory"; "he proposed a fresh theory of alkalis that later was accepted in chemical practices" Synonyms: theory, possibility
	3.	hypothesis - a message expressing an opinion based on incomplete evidence Synonyms: guess, speculation, supposition, surmisal, surmise, conjecture

a priori principle, affirmation, apriorism, assertion, assumed position, assumption, axiom, basis, categorical proposition, conjecture, data, first principles, foundation, ground, guesswork, hypothesis ad hoc, inference, lemma, major premise, minor premise, philosopheme, philosophical proposition, position, postulate, postulation, postulatum, premise, premiss, presumption, presupposal, presupposition, proposition, propositional function, set of postulates, speculation, statement, sumption, supposal, supposing, surmise, theorem, thesis, truth table, truth-function, truth-value, working hypothesis