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.

An hypothesis being a mere supposition, there are no other limits to hypotheses than those of the human imagination.

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.

• A tentative conjecture explaining an observation, phenomenon, or scientific problem that can be tested by further investigation
  
• an assumption taken to be true for the purpose of argument or investigation
  
• (grammar) the antecedent of a conditional statement