e???sist, n. syn: See theory. hy??poth??e??sis (h??-p??th?????-s??s) Plural hypotheses (h??-p??th?????-s??z???) A statement that explains a set of facts and can be tested to determine if it is false or inaccurate.Usage The words hypothesis, law, and theory refer to different kinds of statements that scientists make about natural phenomena.