The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

         A place of potency and away o' the state. --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

potency
    n 1: the power or right to give orders or make decisions; "he
         has the authority to issue warrants"; "deputies are given
         authorization to make arrests"; "a place of potency in the
         state" [syn: authority, authorization, authorisation,
         potency, dominance, say-so]
    2: capacity to produce strong physiological or chemical effects;
       "the toxin's potency"; "the strength of the drinks" [syn:
       potency, effectiveness, strength]
    3: the inherent capacity for coming into being [syn:
       potential, potentiality, potency]
    4: the state of being potent; a male's capacity to have sexual
       intercourse [syn: potency, potence] [ant: impotence,
       impotency]

Moby Thesaurus II by Grady Ward, 1.0:

168 Moby Thesaurus words for "potency":
   amperage, armipotence, ascendancy, authoritativeness, authority,
   beef, birr, black power, brute force, capability, carnality,
   charge, charisma, charm, clout, cogence, cogency, coldness,
   compulsion, consequence, control, credit, decisiveness,
   demonic energy, dint, dominance, domination, drive, duress,
   dynamism, effect, effectiveness, effectuality, efficiency,
   eminence, enchantment, endurance, energy, ergal, esteem, favor,
   flesh, fleshliness, flower power, force, force majeure,
   forcefulness, fortitude, frigidity, full blast, full force, go,
   good feeling, guts, gutsiness, hardihood, hardiness, heartiness,
   hold, importance, impotence, incidental power, influence,
   influentiality, insinuation, intensity, intestinal fortitude,
   kinetic energy, leadership, leverage, libido, love, lovemaking,
   lustihood, lustiness, machismo, magisterialness, magnetism,
   main force, main strength, mana, manly vigor, marriage, mastery,
   might, might and main, mightiness, moment, moxie, muscle,
   muscle power, obstinacy, pep, personality, persuasion, pizzazz,
   poop, potence, potential energy, potentiality, power, power pack,
   power structure, power struggle, powerfulness, predominance,
   preponderance, prepotency, pressure, prestige, productiveness,
   productivity, puissance, pull, punch, purchase, push, reign,
   repute, robustness, ruggedness, rule, say, sensuality, sex drive,
   sexiness, sexual instinct, sexual power, sexual urge, sexualism,
   sexuality, sinew, stalwartness, stamina, staying power, steam,
   sticking power, stoutness, strength, strength of will,
   strenuousness, strong arm, sturdiness, suasion, subtle influence,
   suggestion, superiority, superpower, supremacy, sway, toughness,
   tuck, ultramasculinity, upper hand, validity, vehemence, vigor,
   vigorousness, vim, virileness, virility, virtue, virulence,
   vitality, voluptuousness, wattage, weight, whip hand