MONOGRAM, originally a cipher consisting of a single letter, now a design or mark consisting of two or more letters intertwined together. The letters thus interlaced may be either all the letters of a name or the initial letters of the Christian and surnames of a person for use upon note-paper, seals, etc. Many of the early Greek and Roman coins bear the monograms of rulers for whom, or the towns in which, they were struck. The late Latin and Greek words were first applied to the signatures, which took this form, of the emperors of the eastern empire. The signatures of the Frank ish kings also took the form of a monogram. The most famous of monograms is that known as the "Sacred Monogram," formed by the conjunction of the two initial letters of xptar6s, Christ. The most usual form of this is the symbol ;; and sometimes the a (alpha) and w (omega) of the Apocalypse were placed on each side of it. The symbol was incorporated in the Labarum (q.v.) when the imperial standard was christianized. The inter laced I.H.S. (also called the "Sacred Monogram") apparently possesses no great antiquity; it is said to have been the creation of St. Bernard of Siena in the middle of the 15th century. Mono grams or ciphers were of ten used by the early printers as devices, and are of importance in fixing the identity of early printed books. Similar devices have been used by painters and engravers. The middle ages were, indeed, extremely prolific in the invention of ciphers alike for ecclesiastical, artistic and commercial use.
Every great personage, every possessor of fine taste, every artist, had his monogram. The mason's mark also was, in effect, a cipher. As the merchant had as a rule neither right nor authority to employ heraldic emblems, he, therefore, fell back upon plain simple letters arranged very much in monogram form. These "merchants' marks" generally took the form of a monogram of the owner's initials together with a private device. They nearly always contain a cross, either as a protection against storms or other catastrophes, or as a Christian mark to distinguish their goods from Mohammedan traders in the East. There is a fine ex ample of a 16th century gold ring with a merchant's mark in the British Museum. One of the most famous of secular monograms is the interlaced "H.D." of Henri II. and Diane de Poitiers. Upon every building which that king erected it was sown profusely; it was stamped upon the bindings in the royal library, together with the bow, the quiver and the interlocked crescents of Diana. Henri IV. devised a punning cipher for his mistress Gabrielle d'Estrees, the surname being represented by a capital S. with a trait or stroke through it.
See Du Cange, Glossarium (s.v. Monogramma), with plates giving examples of the monograms of early popes, the emperors of the Western Empire, and of other kings.