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In heraldry, an annulet (i.e. "little ring") is a common charge,[1] which can be described as a roundel that has been "voided" (i.e. with its centre cut out).[2]
In the 19th century, it was theorised by Webster's Dictionary to be related to the custom of prelates to receive their investiture per baculum et annulum ('by rod and ring').[3] In English and Canadian heraldry it is also used as the difference mark of a fifth son.[1][4]