The Collaborative International Dictionary of English v.0.48:

Potential \Po*ten"tial\, a. [Cf. F. potentiel. See Potency.]
   1. Being potent; endowed with energy adequate to a result;
      efficacious; influential. [Obs.] "And hath in his effect a
      voice potential." --Shak.
      [1913 Webster]

   2. Existing in possibility, not in actuality. "A potential
      hero." --Carlyle.
      [1913 Webster]

            Potential existence means merely that the thing may
            be at ome time; actual existence, that it now is.
                                                  --Sir W.
                                                  Hamilton.
      [1913 Webster]

   Potential cautery. See under Cautery.

   Potential energy. (Mech.) See the Note under Energy.

   Potential mood, or Potential mode (Gram.), that form of
      the verb which is used to express possibility, liberty,
      power, will, obligation, or necessity, by the use of may,
      can, must, might, could, would, or should; as, I may go;
      he can write.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Potential \Po*ten"tial\, n.
   1. Anything that may be possible; a possibility; potentially.
      --Bacon.
      [1913 Webster]

   2. (Math.) In the theory of gravitation, or of other forces
      acting in space, a function of the rectangular coordinates
      which determine the position of a point, such that its
      differential coefficients with respect to the coordinates
      are equal to the components of the force at the point
      considered; -- also called potential function, or force
      function. It is called also Newtonian potential when
      the force is directed to a fixed center and is inversely
      as the square of the distance from the center.
      [1913 Webster]

   3. (Elec.) The energy of an electrical charge measured by its
      power to do work; hence, the degree of electrification as
      referred to some standard, as that of the earth;
      electro-motive force.
      [1913 Webster]

WordNet (r) 3.0 (2006):

potential
    adj 1: existing in possibility; "a potential problem"; "possible
           uses of nuclear power" [syn: potential, possible]
           [ant: actual, existent]
    2: expected to become or be; in prospect; "potential clients"
       [syn: likely, potential]
    n 1: the inherent capacity for coming into being [syn:
         potential, potentiality, potency]
    2: the difference in electrical charge between two points in a
       circuit expressed in volts [syn: electric potential,
       potential, potential difference, potential drop,
       voltage]

Moby Thesaurus II by Grady Ward, 1.0:

127 Moby Thesaurus words for "potential":
   EMF, ability, aptitude, bare possibility, between the lines,
   budding, bump, caliber, capability, capacity, chance, cogitable,
   concealed, conceivability, conceivable, conceivableness,
   conceivably possible, conditional, contingency, contingent, covert,
   cryptic, delitescent, developing, dormant, dower, dowry,
   electric potential, electromotive force, electromotivity,
   embryonic, endowment, equipment, esoteric, even chance,
   eventuality, faculty, flair, forte, future, genius, gift,
   good chance, good possibility, hibernating, hidden, hope,
   humanly possible, imaginable, imminent, imperative, implicit,
   implied, indicative, instinct, jussive, latent, likelihood, likely,
   long suit, lurking, makings, metier, mode, mood, muffled, mystic,
   natural endowment, natural gift, obfuscated, obligative, obscured,
   occult, off chance, optative, outside chance, outside hope, parts,
   passive, permissive, plausible, possibilities, possibility,
   possible, possibleness, potency, potential difference,
   potentiality, power, powers, probability, probable, prospect,
   qualification, quiescent, remote possibility, sleeping, small hope,
   speciality, strong flair, strong point, subjunctive, submerged,
   talent, talents, the attainable, the feasible, the goods,
   the possible, the stuff, thinkability, thinkable, thinkableness,
   under the surface, underlying, undeveloped, unmanifested,
   unrealized, veiled, virtual, virtuality, volt, voltage,
   what is possible, what it takes, what may be, what might be