A Christogram is a monogram or combination of letters that forms an abbreviation for the name of Jesus Christ, traditionally used as a religious symbol within the Christian Church. One of the oldest Christograms is the Chi-Rho. It consists of the superimposed Greek letters chi and rho, which are the first two letters of Greek χριστός "Christ". It was displayed on the labarum military standard used by Constantine I in AD 312. The IX monogram is a similar form, using the initials of the name Ἰησοῦς Χριστός "Jesus Christ", as is the ΙΗ monogram, using the first two letters of the name ΙΗΣΟΥΣ "JESUS" in uppercase. There were a very considerable number of variants of "Christograms" or monograms of Christ in use during the medieval period, with the boundary between specific monograms and mere scribal abbreviations somewhat fluid. The name Jesus, spelt "ΙΗΣΟΥΣ" in Greek capitals, has the abbreviations IHS, the name Christus, spelt "ΧΡΙΣΤΟΣ", has XP. In Eastern Christian tradition, the monogram ΙϹΧϹ is used for Ἰησοῦς Χριστός in both Greek and Cyrillic tradition. A Middle Latin term for abbreviations of the name of Christ is chrisimus. Similarly, Middle Latin:wikt:crismon|crismon, chrismon refers to the Chi Rho monogram specifically.
In antiquity, the cross, i.e. the instrument of Christ's crucifixion, was taken to be T-shaped, while the X-shape had different connotations. There has been scholarly speculation on the development of the Christian cross, the letter Chi used to abbreviate the name of Christ, and the various pre-Christian symbolism associated with the chiasmus interpreted in terms of "the mystery of the pre-existent Christ". In Plato's Timaeus, it is explained that the two bands which form the "world soul" cross each other like the letter chi, possibly referring to the ecliptic crossing the celestial equator. Justin Martyr in the 2nd century makes explicit reference to Plato's image in Timaeus in terms of a prefiguration of the Holy Cross. An early statement may be the phrase in Didache, "sign of extension in heaven". An alternative explanation of the intersecting celestial symbol has been advanced by George Latura, claiming that Plato's "visible god" in Timaeus is the intersection of the Milky Way and the Zodiacal Light, a rare apparition important to pagan beliefs. He said that Christian bishops reframed this as a Christian symbol. The most commonly encountered Christogram in English-speaking countries in modern times is the Χ, representing the first letter of the wordChrist, in such abbreviations as Xmas and Xian or Xtian.
The Alpha and Omega symbols may at times accompany the Chi-Rho monogram. :wikt:chrismon|Chrismon since the 17th century has been used as a New Latin term for the Chi Rho monogram. Because the chrismon was used as a kind of "invocation" at the beginning of documents of the Merovingian period, the term also came to be used of the "cross-signatures" in early medieval charters. Chrismon in this context may refer to the Merovingian period abbreviation I. C. N. for in Christi nomine, later also I. C. for in Christo, and still later just C. for Christus. St Cuthbert's coffin has an exceptional realisation of the Christogram written in Anglo-Saxon runes, as ᛁᚻᛋ ᛉᛈᛋ, as it were "IHS XPS", with the chi rendered as the eolh rune and the rho rendered as the p-rune.
IHS
In the Latin-speaking Christianity of medieval Western Europe, the most common Christogram became "IHS" or "IHC", denoting the first three letters of the Greek name of Jesus, ΙΗΣΟΥΣ, iota-eta-sigma, or ΙΗΣ. The Greek letter iota is represented by I, and the eta by H, while the Greek letter sigma is either in its lunate form, represented by C, or its final form, represented by S. Because the Latin-alphabet letters I and J were not systematically distinguished until the 17th century, "JHS" and "JHC" are equivalent to "IHS" and "IHC". "IHS" is sometimes interpreted as meaning "ΙΗΣΟΥΣ ΗΜΕΤΕΡΟΣ ΣΩΤΗΡ" or in Latin "Jesus Hominum Salvator", or connected with In Hoc Signo. English-language interpretations of "IHS" have included "In His Service". Such interpretations are known as backformed acronyms. Used in Latin since the seventh century, the first use of IHS in an English document dates from the fourteenth century, in the vision of William concerning Piers Plowman. In the 15th century, Saint Bernardino of Siena popularized the use of the three letters on the background of a blazing sun to displace both popular pagan symbols and seals of political factions like the Guelphs and Ghibellinesin public spaces. The IHS monogram with the H surmounted by a cross above three nails and surrounded by a Sun is the emblem of the Jesuits, according to tradition introduced by Ignatius of Loyola in 1541.
ICXC
In Eastern Christianity, the most widely used Christogram is a four-letter abbreviation, ΙϹ ΧϹ—a traditional abbreviation of the Greek words for "Jesus Christ", and written with titlo denoting scribal abbreviation. On icons, this Christogram may be split: "ΙϹ" on the left of the image and "ΧϹ" on the right. It is sometimes rendered as "ΙϹ ΧϹ ΝΙΚΑ", meaning "Jesus Christ Conquers." "ΙϹΧϹ" may also be seen inscribed on the Ichthys.
