1832, originally in reference to a 15c.-16c. architectural style with wavy, flame-like curves, from French flamboyant "flaming, wavy," present participle of flamboyer "to flame," from Old French flamboiier "to flame, flare, blaze, glow, shine" (12c.), from flambe "a flame, flame of love," from flamble, variant of flamme, from Latin flammula "little flame," diminutive of flamma "flame, blazing fire" (from PIE root *bhel- (1) "to shine, flash, burn"). Extended sense of "showy, ornate" is from 1879. Related: Flamboyantly.
1757, "military position detached from the main body of troops or outside the limits of a camp," from out- + post (n.2). Originally in George Washington's letters. Phrase outpost of Empire (by 1895) "remotest territory of an empire" in later use often echoes Kipling:
There he shall blaze a nation’s ways with hatchet and with brand,
Till on his last-won wilderness an Empire’s outposts stand!
1730, hypothetical inflammatory principle, formerly believed to exist in all combustible matter, from Modern Latin (1702), from Greek phlogiston (1610s in this sense), neuter of phlogistos "burnt up, inflammable," from phlogizein "to set on fire, burn," from phlox (genitive phlogos) "flame, blaze" (from PIE root *bhel- (1) "to shine, flash, burn"). The theory was propounded by Stahl (1702), denied by Lavoisier (1775), defended by Priestley, but generally abandoned by 1800. Related: Phlogistic; phlogisticated.
late 14c., bluschen, blischen, "to shine brightly; to look, gaze, stare," probably from Old English blyscan "blush, become red, glow" (glossing Latin rutilare), akin to blyse "torch," from Proto-Germanic *blisk- "to shine, burn," which also yielded words in Low German (Dutch blozen "to blush") and Scandinavian (Danish blusse "to blaze; to blush"); ultimately from PIE *bhel- (1) "to shine, flash, burn."
For vowel evolution, see bury. Sense of "turn red in the face" (from shame, modesty, confusion, etc.) is from c. 1400. Related: Blushed; blushing.
Transitive meaning "to burn, set on fire" is from 1580s. Meaning "break out in violence of passion" is from 1540s; the sense of "unleash invective on a computer network" is from 1980s. Related: Flamed; flaming. To flame out, in reference to jet engines, is from 1950.
late 14c., fleem, fleume, "viscid mucus, discharge from a mucous membrane of the body," also the name of one of the four bodily humors, from Old French fleume (13c., Modern French flegme), from Late Latin phlegma, one of the four humors of the body, from Greek phlegma "morbid, clammy bodily humor caused by heat;" literally "inflammation, flame, fire, heat," from phlegein "to burn," related to phlox (genitive phlogos) "flame, blaze," from PIE *bhleg- "to shine, flash," from root *bhel- (1) "to shine, flash, burn."
The modern form of the word is attested by c. 1660. In old physiology it was the "cold, moist" humor of the body and a predominance of it was believed to cause dullness, lethargy, and apathy, hence phlegmatic.
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.
c. 1300, ballede, "wanting hair in some part where it naturally grows," of uncertain origin. Perhaps with Middle English -ede adjectival suffix, from Celtic bal "white patch, blaze" especially on the head of a horse or other animal (from PIE root *bhel- (1) "to shine, flash, gleam").
Compare, from the same root, Sanskrit bhalam "brightness, forehead," Greek phalos "white," Latin fulcia "coot" (so called for the white patch on its head), Albanian bale "forehead." But connection with ball (n.1), on notion of "smooth, round" also has been suggested, and if not formed from it it was early associated with it. Middle English Compendium says it probably was formed on the root of ball, and compares Old Danish bældet.
Sometimes figurative: "meager" (14c.), "without ornament" (16c.), "open, undisguised" (19c.). Of automobile tires with worn treads, by 1930. Bald eagle is attested by 1680s; so called for its white head.