The Collaborative International Dictionary of English v.0.48:

Repulsion \Re*pul"sion\ (r?-p?l"sh?n), n. [L. repulsio: cf. F.
   r['e]pulsion.]
   1. The act of repulsing or repelling, or the state of being
      repulsed or repelled.
      [1913 Webster]

   2. A feeling of violent offence or disgust; repugnance.
      [1913 Webster]

   3. (Physics) The power, either inherent or due to some
      physical action, by which bodies, or the particles of
      bodies, are made to recede from each other, or to resist
      each other's nearer approach; as, molecular repulsion;
      electrical repulsion.
      [1913 Webster]

WordNet (r) 3.0 (2006):

repulsion
    n 1: the force by which bodies repel one another [syn:
         repulsion, repulsive force] [ant: attraction,
         attractive force]
    2: intense aversion [syn: repugnance, repulsion,
       revulsion, horror]
    3: the act of repulsing or repelling an attack; a successful
       defensive stand [syn: repulsion, standoff]

Moby Thesaurus II by Grady Ward, 1.0:

55 Moby Thesaurus words for "repulsion":
   abhorrence, abomination, allergy, antagonism, antipathy, aversion,
   challenge, cold sweat, combative reaction, complaint,
   counteraction, creeping flesh, defiance, demur, detestation,
   disgust, dispute, dissent, dissentience, enmity, fractiousness,
   hate, hatred, horror, hostility, loathing, mortal horror, nausea,
   negativism, noncooperation, objection, obstinacy, opposition,
   passive resistance, protest, reaction, rebuff, recalcitrance,
   recalcitrancy, recalcitration, refractoriness, reluctance,
   remonstrance, renitence, renitency, repellence, repellency,
   repugnance, repulse, resistance, revolt, shuddering, stand,
   uncooperativeness, withstanding