Source : Webster's Revised Unabridged Dictionary (1913)

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

   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.

   3. Anything having a round form; a roundel.

Source : WordNet®

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