Mark of Cadency
In heraldry, this is a mark on the shields of younger members of families, by which they are distinguished from the elder and from each other.
Related term(s): Heraldry; Shield; Charge (Heraldry); Ordinary; Escutcheon; Crescent
Source information: Wilhelm, Thomas. A Military Dictionary and Gazetteer. Philadelphia: L.R. Hamersly & Co., 1881. 81.