rondel
Ron"del, n. Etym: [Cf. Rondeau, Roundel.] 1. (Fort.) Defn: A small round tower erected at the foot of a bastion. [Obs.] 2. Etym: [F.] (a) Same as Rondeau. (b) 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.