Phlegm is the thick mucus brought up from the chest. Coughing up phlegm, clear the phlegm, thick phlegm.
It is produced by the airways and increases with infection, which is why a productive cough follows a cold. Its colour says less about bacteria than people think. Phlegm was one of the four humours in ancient medicine, and phlegmatic — calm and unexcitable — comes from the temperament it was supposed to produce. Note the silent g.
1nounphlegmThe thick mucus brought up from the chest.
“He had a bad chest infection and kept coughing up phlegm.”
phlegm is a bodily mucus.
Greek phlegma meant flame or inflammation, from phlegein, to burn. It named one of the four humours, and phlegmatic keeps the temperament that humour was said to cause.
Ancient Greek
φλέγμα — flame; inflammation; clammy humor in the body
Latin
phlegma
Middle French
flemme
Old French
fleume
Middle English
flewme
English, today
phlegm
Built from
From Middle English flewme, fleume, fleme, from Old French fleume, Middle French flemme (French flegme), and their source, Latin phlegma, from Ancient Greek φλέγμα (“flame; inflammation; clammy humor in the body”), from φλέγειν (“to burn”). Possible burning sensation when coughing up phlegm. Compare phlox, flagrant, flame, bleak, fulminate. Spelling later altered to resemble the word's Latin and Greek roots. The regularly developed form has been displaced by a pronunciation of uncertain provenance. It may be inherited, though some kind of learned or spelling pronunciation or influence from phlegmatic is also conceivable.
Etymology from Wiktionary, CC BY-SA