#1 phlegm n. [emotionlessness, impassivity, impassiveness, indifference, stolidity, unemotionality] apathy demonstrated by an absence of emotional reactions. wn #2 phlegm n. [sputum] expectorated matter; saliva mixed with discharges from the respiratory passages; in ancient and medieval physiology it was believed to cause sluggishness. wn #3 phlegm n. [languor, lethargy, sluggishness, flatness] inactivity; showing an unusual lack of energy; "the general appearance of sluggishness alarmed his friends". wn