Source : Webster's Revised Unabridged Dictionary (1913)

Intension \In*ten"sion\, n. [L. intensio: cf. F. intension. See
   {Intend}, and cf. {Intention}.]
   1. A straining, stretching, or bending; the state of being
      strained; as, the intension of a musical string.

   2. Increase of power or energy of any quality or thing;
      intenseness; fervency. --Jer. Taylor.

            Sounds . . . likewise do rise and fall with the
            intension or remission of the wind.   --Bacon.

   3. (Logic & Metaph.) The collective attributes, qualities, or
      marks that make up a complex general notion; the
      comprehension, content, or connotation; -- opposed to
      {extension}, {extent}, or {sphere}.

            This law is, that the intension of our knowledge is
            in the inverse ratio of its extension. --Sir W.
                                                  Hamilton.

Source : WordNet®

intension
     n : what you must know in order to determine the reference of an
         expression [syn: {connotation}]