c. 1200, savacioun, saluatiun, sauvacioun, etc., originally in the Christian sense, "the saving of the soul, deliverance from the power of sin and admission to eternal bliss," from Old French salvaciun and directly from Late Latin salvationem (nominative salvatio, a Church Latin translation of Greek soteria), noun of action from past-participle stem of salvare "to save" (see save (v.)).
The general (non-religious) sense of "protection or preservation from destruction, danger, calamity, etc." is attested by late 14c. Also from late 14c. as "source, cause, or means of salvation; a preserver, defender." Salvation Army, with quasi-military organization and a mission to spark revival among the masses, is attested from 1878; it was founded 1865 as the Christian Mission by Methodist evangelist the Rev. William Booth (1829-1912).
late 14c., "a circumference; a periphery, a line going around (an area), whether circular or not; a circular or circuitous course," from Old French circuit (14c.) "a circuit; a journey (around something)," from Latin circuitus "a going around," from stem of circuire, circumire "go around," from circum "round" (see circum-) + ire "to go" (from PIE root *ei- "to go").
From c. 1400 as "space enclosed within certain limits." Hence, "district in which any business involving periodic journeys is done (1570s), especially of judicial assignments involving the journey of a judge from one place to another; in reference to routes followed by itinerant entertainers from 1834. Hence also circuit-rider "Methodist minister who rides a circuit, preaching successively in different stations" (by 1834); to ride circuit "take a roundabout course" is from 1650s.
Electrical sense "arrangement by which a current is kept up between two poles" is from 1746. Circuit-breaker "device for automatically opening an electrical circuit" is recorded from 1874. Related: Circuital.