phlegm

Etymology

From Middle English flewme, fleume, fleme, from Old French fleume, Middle French flemme (French flegme), and their source, Latin phlegma, from Ancient Greek φλέγμα (phlégma, “flame; inflammation; clammy humor in the body”), from φλέγειν (phlégein, “to burn”). Compare phlox, flagrant, flame, bleak (adjective), fulminate. Spelling later altered to resemble the word's Latin and Greek roots.

noun

1. (historical) One of the four humors making up the body in ancient and mediaeval medicine; said to be cold and moist, and often identified with mucus.
   Each person's unique mixture of these substances determines his temperament: a predominance of blood gives a sanguine temperament; a predominance of phlegm makes one phlegmatic; yellow bile, bilious (or choleric); and black bile, melancholic. 1993, William Dalrymple, City of Djinns, HarperCollins
2. Viscid mucus produced by the body, later especially mucus expelled from the bronchial passages by coughing.
   Even some members of the new bourgeoisie indulge in conspicuously boorish behavior, like hawking phlegm onto the pavement or picking their noses at business meetings. 2005, "Endangered Species?" Hannah Beech, Time, 14 Nov 2005
3. (historical, chemistry, alchemy) A watery distillation, especially one obtained from plant matter; an aqueous solution.
   The attempts made to analyse vegetable substances previous to 1720, merely produced their resolution into the supposed elements of the chemists of those days, namely, salts, Earths, phlegm, and sulphur. 1812, Humphry Davy, The Elements of Chemical Philosophy, Introduction, Part I. Vol. I, pp. 50-51
4. Calmness of temperament, composure; also seen negatively, sluggishness, indifference.
   Orloff's phlegm broke completely, and he snatched at the monocle as it dropped[.] 1941, Isaac Asimov, The Early Asimov, Volume 2, published 1974, page 180
   But Swedish Nazis also talked of the necessity of saving Sweden from Bolshevism, and with the menacing Berlin radio gnawing in their ears many Swedes lost their Scandinavian phlegm. 5 Oct 1942, “Warning to Sweden”, in Time