The Collaborative International Dictionary of English v.0.48:

Dirge \Dirge\, n. [Contraction of Lat. dirige, direct thou
   (imperative of dirigere), the first word of a funeral hymn
   (Lat. transl. of Psalm v. 8) beginning, "Dirige, Domine, in
   conspectu tuo vitam meam." See Direct, a., and cf.
   Dirige.]
   A piece of music of a mournful character, to accompany
   funeral rites; a funeral hymn.
   [1913 Webster]

         The raven croaked, and hollow shrieks of owls
         Sung dirges at her funeral.              --Ford.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dirge
    n 1: a song or hymn of mourning composed or performed as a
         memorial to a dead person [syn: dirge, coronach,
         lament, requiem, threnody]