The Collaborative International Dictionary of English v.0.48:

Posthumous \Post"hu*mous\ (?; 277), a. [L. posthumus, postumus,
   properly, last; hence, late born (applied to children born
   after the father's death, or after he had made his will),
   superl. of posterus, posterior. See Posterior.]
   1. Born after the death of the father, or taken from the dead
      body of the mother; as, a posthumous son or daughter.
      [1913 Webster]

   2. Published after the death of the author; as, posthumous
      works; a posthumous edition.
      [1913 Webster]

   3. Being or continuing after one's death; as, a posthumous
      reputation. --Addison. --Sir T. Browne.
      [1913 Webster]

WordNet (r) 3.0 (2006):

posthumous
    adj 1: occurring or coming into existence after a person's
           death; "a posthumous award"; "a posthumous book"; "a
           posthumous daughter"