Defervescence \De`fer*ves"cence\, Defervescency \De`fer*ves"cency\, n. [L. defervescere to grow cool.] 1. A subsiding from a state of ebullition; loss of heat; lukewarmness. A defervescency in holy actions. --Jer. Taylor. 2. (Med.) The subsidence of a febrile process; as, the stage of defervescence in pneumonia.