- phlegm
- late 14c., fleem "viscid mucus" (the stuff itself and also regarded as a bodily humor), from O.Fr. fleume (13c., Fr. flegme), from L.L. phlegma, from Gk. phlegma "inflammation, heat, humor caused by heat," from phlegein "to burn," related to phlox (gen. phlogos) "flame, blaze," from PIE *bhleg- "to shine, flash," from base *bhel- (1) "to shine, flash, burn" (see bleach). Modern form is attested from c.1660. The "cold, moist" humor of the body, in medieval physiology, it was believed to cause apathy.