WordNet sense 1 (apathy demonstrated by an absence of emotional reactions):

impassiveness, impassivity, indifference, stolidity, emotionlessness, unemotionality

WordNet sense 2 (expectorated matter; saliva mixed with discharges from the respiratory passages; in ancient and medieval physiology it was believed to cause sluggishness):

sputum

WordNet sense 3 (inactivity; showing an unusual lack of energy):

flatness, languor, lethargy, sluggishness