The Collaborative International Dictionary of English v.0.48:

Roundelay \Round"e*lay\, n. [OF. rondelet, dim. of rondel. See
   Roundel, Roundeau, and cf. Roundlet, Rundlet.]
   1. (Poetry) See Rondeau, and Rondel.
      [1913 Webster]

   2. (Mus.)
      (a) A tune in which a simple strain is often repeated; a
          simple rural strain which is short and lively.
          --Spenser. --Tennyson.
      (b) A dance in a circle.
          [1913 Webster]

   3. Anything having a round form; a roundel.
      [1913 Webster]

WordNet (r) 3.0 (2006):

roundelay
    n 1: a song in which a line or phrase is repeated as the refrain

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "roundelay":
   English sonnet, Horatian ode, Italian sonnet, Petrarchan sonnet,
   Pindaric ode, Sapphic ode, Shakespearean sonnet, alba, anacreontic,
   balada, ballad, ballade, bucolic, canon, canso, catch, chanson,
   clerihew, dirge, dithyramb, eclogue, elegy, epic, epigram,
   epithalamium, epode, epopee, epopoeia, epos, fugato, fugue,
   georgic, ghazel, haiku, idyll, jingle, limerick, lyric, madrigal,
   monody, narrative poem, nursery rhyme, ode, palinode, pastoral,
   pastoral elegy, pastorela, pastourelle, poem, prothalamium, rhyme,
   rondeau, rondel, rondino, rondo, rondoletto, round, roundel,
   satire, sestina, sloka, song, sonnet, sonnet sequence, tanka,
   tenso, tenzone, threnody, triolet, troll, troubadour poem, verse,
   verselet, versicle, villanelle, virelay