Exhaust  —v. 1 consume or use up the whole of. 2 (often as exhausted adj. Or exhausting adj.) Tire out. 3 study or expound (a subject) completely. 4 (often foll. By of) empty (a vessel etc.) Of its contents. —n. 1 waste gases etc. Expelled from an engine after combustion. 2 (also exhaust-pipe) pipe or system by which these are expelled. 3 process of expulsion of these gases.  exhaustible adj. [latin haurio haust- drain]