Definitions
1.NounAnything having a round form; a round figure; a circle."the London Underground roundel"
2.NounA roundelay or rondelay.
3.NounA small circular shield, sometimes not more than a foot in diameter, used by soldiers in the fourteenth and fifteenth centuries.
4.NounA circular spot; a charge in the form of a small coloured circle.
5.NounA circular insignia painted on an aircraft to identify its nationality or service.
6.NounA bastion of a circular form.
7.NounAn umbrella.