EXPANSION, among metaphysicians, denotes the idea we have of lasting distance, all whose parts exist together. Expansion. EXPANSION, in physiology, the swelling or increase of the bulk of bodies when heated. See FIRE and HEAT. Expectorants. EXPECTORANTS, in pharmacy, medicines which promote EXPECTORATION. Expectoration. EXPECTORATION, the act of evacuating or bringing up phlegm or other matters out of the trachea, lungs, &c. by coughing, hawking, spitting, &c. Experience.