phlegm

The story

1. Ancient Greek · derived fromφλέγμα“flame; inflammation; clammy humor in the body”
2. Latin · derived fromphlegma
3. Middle French · derived fromflemme
4. Old French · derived fromfleume
5. Middle English · inherited fromflewme
6. English todayphlegm

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”). Possible burning sensation when coughing up phlegm. Compare phlox, flagrant, flame, bleak (adjective), fulminate. Spelling later altered to resemble the word's Latin and Greek roots. The regularly developed form /fliːm/ has been displaced by a pronunciation /flɛm/ of uncertain provenance. It may be inherited, though some kind of learned or spelling pronunciation or influence from phlegmatic is also conceivable; it dates back to at least the late 1700s, though is probably older.

First known use, by meaning

• from 13th c. 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.
• from 14th c. Viscid mucus produced by the body, later especially mucus expelled from the bronchial passages by coughing.
• from 16th c. A watery distillation, especially one obtained from plant matter; an aqueous solution.
• from 16th c. Calmness of temperament, composure; also seen negatively, sluggishness, indifference.