Rondel

Part of speech: noun (n.)

1. A small round tower erected at the foot of a bastion. [Obs.]

2. Same as Rondeau.

3. Specifically, a particular form of rondeau containing fourteen lines in two rhymes, the refrain being a repetition of the first and second lines as the seventh and eighth, and again as the thirteenth and fourteenth. E. W. Gosse.