‖n. [ NL., fr. Gr. &unr_;, from &unr_; to suppurate; &unr_; in + &unr_; pus. ] (Med.) A collection of blood, pus, or other fluid, in some cavity of the body, especially that of the pleura. Dunglison. [ 1913 Webster ]
☞ The term empyema is now restricted to a collection of pus in the cavity of the pleura. [ 1913 Webster ]