The Collaborative International Dictionary of English v.0.48:

Individualism \In`di*vid"u*al*ism\, n. [Cf. F. individualisme.]
   [1913 Webster]
   [1913 Webster]
   1. The quality of being individual; individuality;
      personality.
      [1913 Webster]

   2. An excessive or exclusive regard to one's personal
      interest; self-interest; selfishness.
      [1913 Webster]

            The selfishness of the small proprietor has been
            described by the best writers as individualism.
                                                  --Ed. Rev.
      [1913 Webster]

   3. The principle, policy, or practice of maintaining
      individuality, or independence of the individual, in
      action; the theory or practice of maintaining the
      independence of individual initiative, action, and
      interests, as in industrial organization or in government.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

individualism
    n 1: the quality of being individual; "so absorbed by the
         movement that she lost all sense of individuality" [syn:
         individuality, individualism, individuation] [ant:
         commonality, commonness]
    2: a belief in the importance of the individual and the virtue
       of self-reliance and personal independence
    3: the doctrine that government should not interfere in
       commercial affairs [syn: individualism, laissez faire]

Moby Thesaurus II by Grady Ward, 1.0:

177 Moby Thesaurus words for "individualism":
   Declaration of Independence, acquisitiveness, animus, aptitude,
   aroma, attribute, autarchy, autarky, autism, autonomy, badge, bent,
   bias, brand, cachet, capitalism, capitalistic system, careerism,
   cast, character, characteristic, complexion, configuration,
   constitution, cut, diathesis, differentia, differential,
   differentiation, differentness, disposition, distinctive feature,
   distinctiveness, earmark, eccentricity, ego, ego trip,
   egocentricity, egocentrism, egohood, egoism, egoisticalness,
   egotism, egotisticalness, feature, figure, finance capitalism,
   flavor, free economy, free enterprise, free-enterprise economy,
   free-enterprise system, grain, graspingness, greed, gust, hallmark,
   home rule, human factor, humor, identity, idiocrasy, idiosyncrasy,
   impress, impression, inclination, independence, index,
   individuality, inner-direction, integrity, interest, keynote,
   kidney, laissez-faire, laissez-faireism, leaning, lineaments, make,
   makeup, mannerism, mark, marking, mental set, mettle, mind,
   mind-set, mold, narcissism, nature, nominalism, nonconformity,
   odor, oneness, particularism, particularity, peculiarity,
   personal aims, personal ambition, personal desires,
   personal equation, personal identity, personalism, personality,
   personship, possessiveness, predilection, predisposition,
   preference, private enterprise, private ownership, private sector,
   privatism, proclivity, propensity, property, quality, quirk,
   remoteness, rugged individualism, savor, seal, self-absorption,
   self-admiration, self-advancement, self-centeredness,
   self-centerment, self-consideration, self-containment,
   self-determination, self-devotion, self-direction, self-esteem,
   self-government, self-identity, self-indulgence, self-interest,
   self-interestedness, self-jealousy, self-occupation, self-pleasing,
   self-reliance, self-seeking, self-serving, self-solicitude,
   self-sufficiency, selfhood, selfishness, selfism, selfness, set,
   shape, singularity, slant, smack, soul, specialty, stamp,
   state capitalism, strain, streak, stripe, taint, tang, taste,
   temper, temperament, tendency, token, trait, trick, turn,
   turn of mind, twist, type, uniqueness, warp