roundlet

noun

1. A small disk, circle or other round object.

   “[…] let the water continue on the fire a Pater noster while, then take it off, and being cold, put the ſame into ſome roundlet, filling the roundlet brim full.”

   “The annexed arrangements of roundlets in shields will show how they are placed and described.”

   “The basis of the chaperon was a wreath-like pad, called a bourlet or roundlet (not unlike a miniature motor-tyre), encircling the temples.”