(1):

(n.) A narrow circle of some distinct color on a surface or round an organ.

(2):

(n.) A little circle borne as a charge.

(3):

(n.) A little ring.

(4):

(n.) 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.