roundel

UK: /ˈraʊnd^əl/ US: (roun′dl)

WordReference Random House Unabridged Dictionary of American English © 2025

roun•del  (roun′dl), n. 

1. something round or circular.
2. a small, round pane or window.
3. a decorative plate, panel, tablet, or the like, round in form.
4. Show Business Also, rondel. [Theat.] a round piece of colored gelatin or glass placed over stage lights as a color medium to obtain lighting effects.
5. Heraldry [Armor.]
   • a metal disk that protects the armpit.
   • a metal disk on a hafted weapon or a dagger to protect the hand.
6. Heraldry a small circular charge.
7. Poetry [Pros.]
   • a rondel or rondeau.
   • a modification of the rondeau, consisting of nine lines with two refrains.
8. Music and Dance a round dance.

• Old French rondel, derivative of rond round¹ (adjective, adjectival)
• Middle English roundele, rundel(le) 1250–1300

Collins Concise English Dictionary © HarperCollins Publishers::

roundel / ˈraʊnd^əl/ noun

1. a form of rondeau consisting of three stanzas each of three lines with a refrain after the first and the third
2. a circular identifying mark in national colours on military aircraft
3. a small ornamental circular window, panel, medallion, plate, disc, etc
4. a round plate of armour used to protect the armpit
5. another word for roundelay1

Etymology: 13th Century: from Old French rondel a little circle; see rondel