Source : Webster's Revised Unabridged Dictionary (1913)

Valedictory \Val`e*dic"to*ry\, a.
   Bidding farewell; suitable or designed for an occasion of
   leave-taking; as, a valedictory oration.

Valedictory \Val`e*dic"to*ry\, n.; pl. {Valedictories}.
   A valedictory oration or address spoken at commencement in
   American colleges or seminaries by one of the graduating
   class, usually by the leading scholar.

Source : WordNet®

valedictory
     adj 1: of or relating to an occasion or expression of farewell; "a
            valedictory address"; "valedictory praise for his
            uniformly manly course"; "a suitable valedictory
            gesture"
     2: of a speech expressing leave-taking; "a valedictory address"

valedictory
     n : a farewell oration delivered by the most outstanding member
         of a graduating class [syn: {valediction}, {valedictory
         address}]