Hypothesis

Part of speech: noun (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. 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.

Synonyms: Supposition; assumption. See Theory. Nebular hypothesis. See under Nebular.