n. 1 the thick viscous substance secreted by the mucous membranes of the respiratory passages, discharged by coughing. 2 a coolness and calmness of disposition. b sluggishness or apathy (supposed to result from too much phlegm in the constitution). 3 archaic phlegm regarded as one of the four bodily humours. phlegmy adj.
[ ME & OF fleume f. LL phlegma f. Gk phlegma -atos inflammation f. phlego burn ]