The Collaborative International Dictionary of English v.0.48:

Elegiac \E*le"gi*ac\ (?; 277), a. [L. elegiacus, Gr. ?: cf. F.
   ['e]l['e]giaque. See Elegy.]
   1. Belonging to elegy, or written in elegiacs; plaintive;
      expressing sorrow or lamentation; as, an elegiac lay;
      elegiac strains.
      [1913 Webster]

            Elegiac griefs, and songs of love.    --Mrs.
                                                  Browning.
      [1913 Webster]

   2. Used in elegies; as, elegiac verse; the elegiac distich or
      couplet, consisting of a dactylic hexameter and
      pentameter.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Elegiac \E*le"gi*ac\, n.
   Elegiac verse.
   [1913 Webster]

WordNet (r) 3.0 (2006):

elegiac
    adj 1: resembling or characteristic of or appropriate to an
           elegy; "an elegiac poem on a friend's death"
    2: expressing sorrow often for something past; "an elegiac
       lament for youthful ideals"

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "elegiac":
   Alcaic, Anacreontic, Castalian, Homeric, Hudibrastic, Pierian,
   Pindaric, Theocritean, bardic, bucolic, didactic, dirgelike,
   dithyrambic, dramatic, eclogic, epic, heroic, idyllic, knell-like,
   mock-heroic, narrative, pastoral, poetic, poetico-mystical,
   poetico-mythological, poetico-philosophic, poetlike, rhapsodic,
   runic, sapphic, skaldic, threnodic