Source : Webster's Revised Unabridged Dictionary (1913)

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.

            Elegiac griefs, and songs of love.    --Mrs.
                                                  Browning.

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

Elegiac \E*le"gi*ac\, n.
   Elegiac verse.

Source : WordNet®

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"