Old English hælan "cure; save; make whole, sound and well," from Proto-Germanic *hailjan (source also of Old Saxon helian, Old Norse heila, Old Frisian hela, Dutch helen, German heilen, Gothic ga-hailjan "to heal, cure"), literally "to make whole" (from PIE *kailo- "whole;" see health). Intransitive sense from late 14c. Related: Healed; healing.
"restoration to health," Old English hæling, verbal noun from heal (v.). Figurative sense of "restoration of wholeness" is from early 13c.; meaning "touch that cures" is from 1670s.
late Old English, "one who heals," especially "savior, Jesus," agent noun from heal (v.). As "a curative medicine" from late 14c. The usual Old English noun for Jesus as savior was hæland (Middle English healend), a noun use of a present participle, being a rough translation of the name (see Joshua) or of Latin salvator.
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]
early 15c., "pertaining to curing; having the power to heal," from Old French curatif (15c.) "curative, healing" and directly from Latin curat-, past-participle stem of curare "to cure" (see cure (v.)). As a noun, "something that has power to heal, a remedy," by 1857.
"admitting of medical treatment, curable, healable," 1610s, from Latin medicabilis "curable," from medicare, medicari "to medicate, heal, cure" (poetic and Late Latin) from medicus "physician, healing" (see medical (adj.)).