adj a bastion of a circular form.
2. roundel ·adj a rondelay.
3. roundel ·adj anything having a round form; a round figure; a circle.
4. roundel ·adj a circular spot; a sharge in the form of a small circle.
5. roundel ·adj a small circular shield, sometimes not more than a foot in diameter, used by soldiers in the fourteenth and fifteenth centuries.