IHS is a monogram for the name of Jesus, using the first three letters of the word written in Greek. From the third century the names of our Savior are sometimes shortened, particularly in Christian inscriptions. Greek monograms for the sacred name continued to be used in Latin during the Middle Ages.
In the Middle Ages, it was erroneously thought that IHS stood for Jesus Hominum Salvator (Jesus, Savior of Men) or the popular English, “I have suffered.” It is found as a sign for the Holy Name of Jesus.
The letters INRI, to be found inscribed above the head of the figure of the crucified Christ, the “corpus,” on most crucifixes, are the initials for the inscription which Pontius Pilate had placed on the cross of Our Lord, as the charge for which the Lord was crucified.
The Gospels give accounts of this inscription, stating that Pilate put “Jesus of Nazareth (literally, the Nazarene), King of the Jews.” The Gospels tell us that this was inscribed in Hebrew, Latin and Greek.
INRI stands for the initials of the Latin inscription Iesus Nazarenus, Rex Iudaeorum. (9:9)