Definition of "rondel"

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.  examples

The verse form rondeau.  examples

A rondelle, (small) circular object.  examples

(historical) A long thin medieval dagger with a circular guard and a circular pommel (hence the name).

(historical) A small round tower erected at the foot of a bastion.