Source : Webster's Revised Unabridged Dictionary (1913)

Theorem \The"o*rem\, n. [L. theorema, Gr. ? a sight,
   speculation, theory, theorem, fr. ? to look at, ? a
   spectator: cf. F. th['e]or[`e]me. See {Theory}.]
   1. That which is considered and established as a principle;
      hence, sometimes, a rule.

            Not theories, but theorems (?), the intelligible
            products of contemplation, intellectual objects in
            the mind, and of and for the mind exclusively.
                                                  --Coleridge.

            By the theorems, Which your polite and terser
            gallants practice, I re-refine the court, and
            civilize Their barbarous natures.     --Massinger.

   2. (Math.) A statement of a principle to be demonstrated.

   Note: A theorem is something to be proved, and is thus
         distinguished from a problem, which is something to be
         solved. In analysis, the term is sometimes applied to a
         rule, especially a rule or statement of relations
         expressed in a formula or by symbols; as, the binomial
         theorem; Taylor's theorem. See the Note under
         {Proposition}, n., 5.

   {Binomial theorem}. (Math.) See under {Binomial}.

   {Negative theorem}, a theorem which expresses the
      impossibility of any assertion.

   {Particular theorem} (Math.), a theorem which extends only to
      a particular quantity.

   {Theorem of Pappus}. (Math.) See {Centrobaric method}, under
      {Centrobaric}.

   {Universal theorem} (Math.), a theorem which extends to any
      quantity without restriction.