c. 1300, saveour, "one who delivers or rescues from peril," also a title of Jesus Christ, from Old French sauveour, from Late Latin salvatorem (nominative salvator) "a saver, preserver," originally and chiefly Church Latin, with reference to Christ (source also of Spanish salvador, Italian salvatore), from salvatus, past participle of salvare "to save" (see save (v.)). In the New Testament used of both Jesus and God.
In the Christian sense, the Latin noun is a translation of Greek sōtēr "savior." In English, it replaced Old English hælend, literally "healing," likely a loan-translation from Latin, a noun use of the present participle of hælan (see heal). Middle English also had salvatour "Jesus Christ," also "a rescuer" (c. 1300) from the Latin, and compare saver. The conservatism of liturgy sustained the -our spelling (see -or).
The old spelling saviour still prevails even where other nouns in -our, esp. agent-nouns, are now spelled with -or, the form savior being regarded by some as irreverent. [Century Dictionary, 1895]
updated on January 08, 2022