Rondel

noun

1. A metric form of verse using two rhymes, usually fourteen 8- to 10-syllable lines in three stanzas, with the first lines of the first stanza returning as refrain of the next two.
2. The verse form rondeau.
3. A rondelle, (small) circular object.
4. A long thin medieval dagger with a circular guard and a circular pommel (hence the name).
5. A small round tower erected at the foot of a bastion.