To remove a resource from; deplete, To let out or draw off (a gas, for example) from a container, transitive verb_ To empty by drawing or letting out the contents, To draw or let out wholly; to drain off completely, verb_ To bring out or develop completely; to discuss thoroughly; as, to exhaust a subject, To empty by drawing or letting out the contents; as, to exhaust a well, or a treasury, noun_ A system consisting of the parts of an engine through which burned gases or steam are discharged; see also exhaust system, The steam let out of a cylinder after it has done its work there