The Collaborative International Dictionary of English v.0.48:

Dedication \Ded`i*ca"tion\, n. [L. dedicatio.]
   1. The act of setting apart or consecrating to a divine
      Being, or to a sacred use, often with religious
      solemnities; solemn appropriation; as, the dedication of
      Solomon's temple.
      [1913 Webster]

   2. A devoting or setting aside for any particular purpose;
      as, a dedication of lands to public use.
      [1913 Webster]

   3. An address to a patron or friend, prefixed to a book,
      testifying respect, and often recommending the work to his
      special protection and favor.
      [1913 Webster]

WordNet (r) 3.0 (2006):

dedication
    n 1: complete and wholehearted fidelity
    2: a ceremony in which something (as a building) is dedicated to
       some goal or purpose
    3: a message that makes a pledge [syn: commitment,
       dedication]
    4: a short message (as in a book or musical work or on a
       photograph) dedicating it to someone or something [syn:
       dedication, inscription]
    5: the act of binding yourself (intellectually or emotionally)
       to a course of action; "his long commitment to public
       service"; "they felt no loyalty to a losing team" [syn:
       commitment, allegiance, loyalty, dedication]