The Collaborative International Dictionary of English v.0.48:

Legitimation \Le*git`i*ma"tion\ (-m[=a]"sh[u^]n), n. [Cf. F.
   l['e]gitimation.]
   [1913 Webster]
   1. The act of making legitimate.
      [1913 Webster]

            The coining or legitimation of money. --East.
      [1913 Webster]

   2. Lawful birth. [R.] --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

legitimation
    n 1: the act of rendering a person legitimate; "he has filial
         rights because he obtained letters of legitimation from the
         king"; "his parents' subsequent marriage resulted in his
         legitimation"
    2: the act of making lawful [syn: legalization,
       legalisation, legitimation]