\Ex*haust"\, v. t. [imp. & p. p. {Exhausted}; p. pr. &
vb. n. {Exhausting}.] [L. exhaustus, p. p. of exhaurire; ex
out + haurire, haustum, to draw, esp. water; perhaps akin to
Icel. asua to sprinkle, pump.]
1. To draw or let out wholly; to drain off completely; as, to
   exhaust the water of a well; the moisture of the earth is
   exhausted by evaporation.
2. To empty by drawing or letting out the contents; as, to
   exhaust a well, or a treasury.
3. To drain, metaphorically; to use or expend wholly, or till
   the supply comes to an end; to deprive wholly of strength;
   to use up; to weary or tire out; to wear out; as, to
   exhaust one's strength, patience, or resources.
         A decrepit, exhausted old man at fifty-five.
                                               --Motley.
4. To bring out or develop completely; to discuss thoroughly;
   as, to exhaust a subject.
5. (Chem.) To subject to the action of various solvents in
   order to remove all soluble substances or extractives; as,
   to exhaust a drug successively with water, alcohol, and
   ether.
{Exhausted receiver}. (Physics) See under {Receiver}.
Syn: To spend; consume; tire out; weary.

\Ex*haust"\, a. [L. exhaustus, p. p.]
1. Drained; exhausted; having expended or lost its energy.
2. Pertaining to steam, air, gas, etc., that is released from
   the cylinder of an engine after having preformed its work.
{Exhaust draught}, a forced draught produced by drawing air
   through a place, as through a furnace, instead of blowing
   it through.
{Exhaust fan}, a fan blower so arranged as to produce an
   exhaust draught, or to draw air or gas out of a place, as
   out of a room in ventilating it.
{Exhaust nozzle}, {Exhaust orifice} (Steam Engine), the blast
   orifice or nozzle.
{Exhaust pipe} (Steam Engine), the pipe that conveys exhaust
   steam from the cylinder to the atmosphere or to the
   condenser.
{Exhaust port} (Steam Engine), the opening, in the cylinder
   or valve, by which the exhaust steam escapes.
{Exhaust purifier} (Milling), a machine for sorting grains,
   or purifying middlings by an exhaust draught. --Knight.
{Exhaust steam} (Steam Engine), steam which is allowed to
   escape from the cylinder after having been employed to
   produce motion of the piston.
{Exhaust valve} (Steam Engine), a valve that lets exhaust
   steam escape out of a cylinder.

\Ex*haust"\, n. (Steam Engine)
1. The steam let out of a cylinder after it has done its work
   there.
2. The foul air let out of a room through a register or pipe
   provided for the purpose.