annulet

noun

1. Also called bandelet, bandlet, square and rabbet. Architecture. an encircling band, molding, or fillet, as on the shaft of a column.
2. Entomology. a ring, usually colored, around or on the surface of an organ.
3. Heraldry. a ring, represented as a voided roundel, used especially as the cadence mark of a fifth son.

noun

1. architect a moulding in the form of a ring, as at the top of a column adjoining the capital
2. heraldry a ring-shaped device on a shield; hollow roundel
3. a little ring