c. 1300, Messias, a designation of Jesus as the savior of the world, from Late Latin Messias, from Greek Messias, from Aramaic (Semitic) meshiha and Hebrew mashiah "the anointed" (of the Lord), from mashah "anoint." It is thus the Hebrew equivalent of Christ, and it is the word rendered in Septuagint as Greek Khristos (see Christ).
In Old Testament prophetic writing, it was used as a descriptive title of an expected deliverer of the Jewish nation. The modern English form represents an attempt to make the word look more Hebrew, and dates from the Geneva Bible (1560). Transferred sense of "an expected liberator or savior of a captive people" is attested from 1660s. Related: Messiahship "the character, state, or office of Jesus Christ as savior of the world" (1620s).
"relating or pertaining to the Messiah or to anyone exercising the offices of a messiah," 1831, from Modern Latin messianicus, from Messias (see Messiah).
"the Anointed," synonymous with and translating to Greek Hebrew mashiah (see messiah), a title given to Jesus of Nazareth; Old English crist (by 830, perhaps 675), from Latin Christus, from Greek khristos "the anointed," noun use of verbal adjective of khriein "to rub, anoint" (from PIE root *ghrei- "to rub").
In the primitive Church it was a title, and used with the definite article, but from an early period it was used without it and regarded as part of the proper name of Jesus. It was treated as a proper name in Old English, but not regularly capitalized until 17c. Pronunciation with long -i- is result of Irish missionary work in England, 7c.-8c. The ch- form, regular since c. 1500 in English, was rare before. Capitalization of the word begins 14c. but is not fixed until 17c. The Latin term drove out Old English Hæland "healer, savior," as the preferred descriptive term for Jesus.
As an oath or strong exclamation (of surprise, dismay, etc.), attested by 1748. The 17c. mystical sect of the Familists edged it toward a verb with Christed "made one with Christ." Christ-child "Jesus as a baby" (1842) translates German Christkind.