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]

Moby Thesaurus II by Grady Ward, 1.0:

175 Moby Thesaurus words for "dirge":
   Brautlied, Christmas carol, Dry Mass, English sonnet,
   Eucharistic rites, Horatian ode, Italian sonnet, Kunstlied,
   Lady Mass, Liebeslied, Low Mass, Mass, Missa, Missa bassa,
   Missa cantata, Missa legata, Missa media,
   Missa praesanctificatorum, Missa privata, Missa publica,
   Missa sicca, Petrarchan sonnet, Pindaric ode, Requiem Mass, Rosary,
   Rosary Mass, Sapphic ode, Shakespearean sonnet, Volkslied, alba,
   anacreontic, anthem, art song, aubade, balada, ballad, ballade,
   ballata, barcarole, bemoan, bewail, blues, blues song, boat song,
   bridal hymn, brindisi, bucolic, burial service, calypso, canso,
   canticle, canzone, canzonet, canzonetta, carol, cavatina, chanson,
   chant, chantey, clerihew, coronach, croon, croon song, dead march,
   death knell, death song, deathwatch, deplore, dithyramb, ditty,
   drinking song, eclogue, elegize, elegy, epic, epicedium, epigram,
   epithalamium, epode, epopee, epopoeia, epos, eulogy, exequies,
   extreme unction, folk song, funeral march, funeral oration,
   funeral rites, funeral song, georgic, ghazel, give sorrow words,
   graveside oration, grieve, haiku, hymeneal, idyll, jingle, keen,
   knell, lament, last duty, last honors, last offices, last rites,
   lay, lied, lilt, limerick, love song, love-lilt, lyric, madrigal,
   matin, minstrel song, minstrelsy, moan, monody, mourn,
   muffled drums, narrative poem, national anthem, nursery rhyme,
   obsequies, ode, palinode, passing bell, pastoral, pastoral elegy,
   pastorela, pastourelle, poem, prothalamium, repine, requiem,
   requiem mass, rhyme, rondeau, rondel, roundel, roundelay, satire,
   serena, serenade, serenata, sestina, sigh, sing the blues, sloka,
   song, sonnet, sonnet sequence, sorrow, tanka, tenso, tenzone,
   the Divine Liturgy, the Liturgy, theme song, threnode, threnody,
   torch song, triolet, troubadour poem, verse, verselet, versicle,
   viaticum, villanelle, virelay, wake, war song, wedding song,
   weep over