noun a white crystalline substance, nh2·co·oc2h5, produced by the action of ammonia on ethyl carbonate. it is used somewhat in medicine as a hypnotic. by extension, any one of the series of related substances of which urethane proper is the type.
2. urethane ·add. ·noun a white crystalline substance, nh2·cooc2h5, produced by the action of ammonia on ethyl carbonate or by heating urea nitrate and ethyl alcohol. it is used as a hypnotic, antipyretic, and antispasmodic. hence, any ester of carbamic acid.