Noun
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.
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.
Source: Webster's dictionaryThe great tragedy of science - the slaying of a beautiful hypothesis by an ugly fact. Thomas Henry Huxley
A fact is a simple statement that everyone believes. It is innocent, unless found guilty. A hypothesis is a novel suggestion that no one wants to believe. It is guilty, until found effective. Edward Teller
It is a good morning exercise for a research scientist to discard a pet hypothesis every day before breakfast. It keeps him young. Konrad Lorenz
It is an hypothesis that the sun will rise tomorrow: and this means that we do not know whether it will rise. Ludwig Wittgenstein
If I were to awaken after having slept for a thousand years, my first question would be: Has the Riemann hypothesis been proven? David Hilbert
From the standpoint of observation, then, we must regard it as a highly probable hypothesis that the beginnings of the mental life date from as far back as the beginnings of life at large. Wilhelm Wundt