Pressure \Pres"sure\ (?; 138), n. [OF., fr. L. pressura, fr.
   premere. See 4th Press.]
   1. The act of pressing, or the condition of being pressed;
      compression; a squeezing; a crushing; as, a pressure of
      the hand.
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   2. A contrasting force or impulse of any kind; as, the
      pressure of poverty; the pressure of taxes; the pressure
      of motives on the mind; the pressure of civilization.
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            Where the pressure of danger was not felt.
                                                  --Macaulay.
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   3. Affliction; distress; grievance.
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            My people's pressures are grievous.   --Eikon
                                                  Basilike.
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            In the midst of his great troubles and pressures.
                                                  --Atterbury.
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   4. Urgency; as, the pressure of business.
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   5. Impression; stamp; character impressed.
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            All saws of books, all forms, all pressures past.
                                                  --Shak.
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   6. (Mech.) The action of a force against some obstacle or
      opposing force; a force in the nature of a thrust,
      distributed over a surface, often estimated with reference
      to the amount upon a unit's area.
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   7. Electro-motive force.
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   Atmospheric pressure, Center of pressure, etc. See under
      Atmospheric, Center, etc.

   Back pressure (Steam engine), pressure which resists the
      motion of the piston, as the pressure of exhaust steam
      which does not find free outlet.

   Fluid pressure, pressure like that exerted by a fluid. It
      is a thrust which is normal and equally intense in all
      directions around a point. --Rankine.

   Pressure gauge, a gauge for indicating fluid pressure; a
      manometer.
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Back \Back\, a.
   1. Being at the back or in the rear; distant; remote; as, the
      back door; back settlements.
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   2. Being in arrear; overdue; as, back rent.
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   3. Moving or operating backward; as, back action.
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   Back blocks, Australian pastoral country which is remote
      from the seacoast or from a river. [Webster 1913 Suppl.]
      

   Back charges, charges brought forward after an account has
      been made up.

   Back filling (Arch.), the mass of materials used in filling
      up the space between two walls, or between the inner and
      outer faces of a wall, or upon the haunches of an arch or
      vault.

   Back pressure. (Steam Engine) See under Pressure.

   Back rest, a guide attached to the slide rest of a lathe,
      and placed in contact with the work, to steady it in
      turning.

   Back slang, a kind of slang in which every word is written
      or pronounced backwards; as, nam for man.

   Back stairs, stairs in the back part of a house; private
      stairs. Also used adjectively. See Back stairs,
      Backstairs, and Backstair, in the Vocabulary.

   Back step (Mil.), the retrograde movement of a man or body
      of men, without changing front.

   Back stream, a current running against the main current of
      a stream; an eddy.

   To take the back track, to retrace one's steps; to retreat.
      [Colloq.]
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