Annulet

An·nu·let

Annulet

n.
  1. A little ring.
  2. A small, flat fillet, encircling a column, etc., used by itself, or with other moldings. It is used, several times repeated, under the Doric capital. (Arch.)
  3. A little circle borne as a charge. (Her.)
  4. A narrow circle of some distinct color on a surface or round an organ. (Zool.)