The Collaborative International Dictionary of English v.0.48:

Individuation \In`di*vid`u*a"tion\, n. [Cf. F. individuation.]
   The act of individuating or state of being individuated;
   individualization. --H. Spencer.
   [1913 Webster]

WordNet (r) 3.0 (2006):

individuation
    n 1: discriminating the individual from the generic group or
         species [syn: individualization, individualisation,
         individuation]
    2: the quality of being individual; "so absorbed by the movement
       that she lost all sense of individuality" [syn:
       individuality, individualism, individuation] [ant:
       commonality, commonness]