The Collaborative International Dictionary of English v.0.48:

Atmospheric \At`mos*pher"ic\, Atmospherical \At`mos*pher"ic*al\,
   a. [Cf. F. atmosph['e]rique.]
   1. Of or pertaining to the atmosphere; of the nature of, or
      resembling, the atmosphere; as, atmospheric air; the
      atmospheric envelope of the earth.
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   2. Existing or occurring in the atmosphere.
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            The lower atmospheric current.        --Darwin.
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   3. Caused, or operated on, by the atmosphere; as, an
      atmospheric effect; an atmospheric engine.
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   4. Dependent on the atmosphere. [R.]
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            In am so atmospherical a creature.    --Pope.
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   Atmospheric engine, a steam engine whose piston descends by
      the pressure of the atmosphere, when the steam which
      raised it is condensed within the cylinder. --Tomlinson.

   Atmospheric line (Steam Engin.), the equilibrium line of an
      indicator card. Steam is expanded "down to the atmosphere"
      when its pressure is equal to that of the atmosphere. (See
      Indicator card.)

   Atmospheric pressure, the pressure exerted by the
      atmosphere, not merely downwards, but in every direction.
      In amounts to about 14.7 Ibs. on each square inch.

   Atmospheric railway, one in which pneumatic power, obtained
      from compressed air or the creation of a vacuum, is the
      propelling force.

   Atmospheric tides. See under Tide.
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