*from George Orwell’s 1984 (1949).
From Online Etymology Dictionary:
c. 1500, “resplendent” (obsolete), from Latin flagrantem (nominative flagrans) “burning, blazing, glowing,” figuratively “glowing with passion, eager, vehement,” present participle of flagrare “to burn, blaze, glow,” from Proto-Italic *flagro-“burning” (source also of Oscan flagio-, an epithet of Iuppiter), corresponding to PIE *bhleg-ro-, from *bhleg– “to shine, flash, burn” (source also of Greek phlegein “to burn, scorch,” Latin fulgere “to shine”), from root *bhel– (1) “to shine, flash, burn.” Sense of “glaringly offensive, scandalous” (rarely used of persons) first recorded 1706, probably from common legalese phrase flagrante delicto “while the crime is being committed, red-handed,” literally “with the crime still blazing.” Related: Flagrantly.
“a setting on fire,” c. 1600, from Latin deflagrationem (nominative deflagratio) “a burning up, conflagration,” noun of action from past-participle stem of deflagrare, from de (see de-) + flagrare “to burn, blaze, glow,” from PIE root *bhel- (1) “to shine, flash, burn.” Related: Deflagrate, deflagrating.
1550s, “a destructive fire;” 1650s, “a large fire, the burning of a large mass of combustibles,” from French conflagration (16c.) or directly from Latin conflagrationem (nominative conflagratio), noun of action from past-participle stem of conflagrare “to burn up,” from assimilated form of com-, here perhaps an intensive prefix (see con-), + flagrare “to burn, blaze, glow” (from PIE root *bhel- (1) “to shine, flash, burn”).”