A rebus (/ˈrē-bəs/) is an allusional device that uses pictures to represent words or parts of words. It was a favourite form of heraldic expression used in the Middle Ages to denote surnames.
For example, in its basic form, three salmon (fish) are used to denote the surname "Salmon". A more sophisticated example was the rebus of Bishop Walter Lyhart (d.1472) of Norwich, consisting of a stag (or hart) lying down in a conventional representation of water.
The composition alludes to the name, profession or personal characteristics of the bearer, and speaks to the beholder Non verbis, sed rebus, which Latin expression signifies "not by words but by things" (res, rei (f), a thing, object, matter; rebus being ablative plural).
Rebuses are used extensively as a form of heraldic expression as a hint to the name of the bearer; they are not synonymous with canting arms. A man might have a rebus as a personal identification device entirely separate from his armorials, canting or otherwise. For example, Sir Richard Weston (d.1541) bore as arms: Ermine, on a chief azure five bezants, whilst his rebus, displayed many times in terracotta plaques on the walls of his mansion Sutton Place, Surrey, was a "tun" or barrel, used to designate the last syllable of his surname.
An example of canting arms proper are those of the Borough of Congleton in Cheshire consisting of a conger eel, a lion (in Latin, leo) and a tun (another word for a barrel). This word sequence "conger-leo-tun" enunciates the town's name. Similarly, the coat of arms of St. Ignatius Loyola contains wolves (in Spanish, lobo) and a kettle (olla), said by some (probably incorrectly) to be a rebus for "Loyola". The arms of Elizabeth Bowes-Lyon feature bows and lions.