Definition of: phlegm

(flem) noun
1. Physiol. A viscid, stringy mucus secreted in the air passages or in the stomach, especially when produced as a morbid discharge.
2. Apathy; indifference; cold, undemonstrative temper; self–possession.
3. Obs. One of the four natural humors (the cold and moist) in ancient physiology. See synonyms under APATHY. [<OF fleume, flemme <L phlegma the clammy humor of the body <Gk., inflammation <phlegein blaze; refashioned after Gk.]