<p><strong>Noun</strong></p><ul><li>a coherent group of tested general propositions, commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena: Einstein's theory of relativity.</li><li>Synonyms: doctrine, law, principle</li><li>a proposed explanation whose status is still conjectural and subject to experimentation, in contrast to well-established propositions that are regarded as reporting matters of actual fact.</li><li>Synonyms: thesis, postulate, concept, notion, idea</li><li>Mathematics: a body of principles, theorems, or the like, belonging to one subject: number theory.</li><li>the branch of a science or art that deals with its principles or methods, as distinguished from its practice: music theory.</li><li>a particular conception or view of something to be done or of the method of doing it; a system of rules or principles: conflicting theories of how children best learn to read.</li><li>contemplation or speculation: the theory that there is life on other planets.</li><li>Synonyms: view, deduction, conclusion, judgment, opinion, thought</li><li>guess or conjecture: My theory is that he never stops to think words have consequences.</li><li>Synonyms: presumption, supposition, surmise, hypothesis</li></ul>