Webster's Revised Unabridged Dictionary · 1913

Roundel

Roundel , noun

[Old French rondel a roundelay, French rondel, rondeau, a dim. from rond; for sense 2, compare French rondelle a round, a round shield. See Round, a., and compare Rondel, Rondelay.]

1.
(Music) A rondelay.
Sung all the roundel lustily. — Chaucer
Come, now a roundel and a fairy song. — Shakespeare
2.
Anything having a round form; a round figure; a circle.
The Spaniards, casting themselves into roundels,... made a flying march to Calais. — Bacon
(a)
(Heraldry) A small circular shield, sometimes not more than a foot in diameter, used by soldiers in the fourteenth and fifteenth centuries.
(b)
(Heraldry) A circular spot; a sharge in the form of a small circle.
(c)
(Heraldry) A bastion of a circular form.