The Collaborative International Dictionary of English v.0.48:

Immortalize \Im*mor"tal*ize\, v. t. [imp. & p. p.
   Immortalized; p. pr. & vb. n. Immortalizing.] [Cf. F.
   immortaliser.]
   1. To render immortal; to cause to live or exist forever.
      --S. Clarke.
      [1913 Webster]

   2. To exempt from oblivion; to perpetuate in fame.
      [1913 Webster]

            Alexander had no Homer to immortalize his guilty
            name.                                 --T. Dawes.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Immortalize \Im*mor"tal*ize\, v. i.
   To become immortal. [R.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

immortalize
    v 1: be or provide a memorial to a person or an event; "This
         sculpture commemorates the victims of the concentration
         camps"; "We memorialized the Dead" [syn: commemorate,
         memorialize, memorialise, immortalize, immortalise,
         record]
    2: make famous forever; "This melody immortalized its composer"
       [syn: immortalize, immortalise, eternize, eternise,
       eternalize, eternalise]