Source : Webster's Revised Unabridged Dictionary (1913)

Potency \Po"ten*cy\, n. [L. potentia, from potens, -entis,
   potent. See {Potent}, and cf. {Potance}, {Potence},
   {Puissance}.]
   The quality or state of being potent; physical or moral
   power; inherent strength; energy; ability to effect a
   purpose; capability; efficacy; influence. ``Drugs of
   potency.'' --Hawthorne.

         A place of potency and away o' the state. --Shak.

Source : WordNet®

potency
     n 1: capacity to produce strong physiological or chemical
          effects; "the toxin's potency"; "the strength of the
          drinks" [syn: {effectiveness}, {strength}]
     2: the inherent capacity for coming into being [syn: {potential},
         {potentiality}]
     3: the state of being potent; a male's capacity to have sexual
        intercourse