abyssal zone
    n 1: the deep sea (2000 meters or more) where there is no light

Zone \Zone\ (z[=o]n), n. [F. zone, L. zona, Gr. zw`nh; akin to
   zwnny`nai to gird, Lith. j[*u]sta a girdle, j[*u]sti to gird,
   Zend y[=a]h.]
   1. A girdle; a cincture. [Poetic]
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            An embroidered zone surrounds her waist. --Dryden.
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            Loose were her tresses seen, her zone unbound.
                                                  --Collins.
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   2. (Geog.) One of the five great divisions of the earth, with
      respect to latitude and temperature.
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   Note: The zones are five: the torrid zone, extending from
         tropic to tropic 46[deg] 56[min], or 23[deg] 28[min] on
         each side of the equator; two temperate or variable
         zones, situated between the tropics and the polar
         circles; and two frigid zones, situated between the
         polar circles and the poles.
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               Commerce . . . defies every wind, outrides every
               tempest, and invades.              --Bancroft.
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   3. (Math.) The portion of the surface of a sphere included
      between two parallel planes; the portion of a surface of
      revolution included between two planes perpendicular to
      the axis. --Davies & Peck (Math. Dict.)
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   4. (Nat. Hist.)
      (a) A band or stripe extending around a body.
      (b) A band or area of growth encircling anything; as, a
          zone of evergreens on a mountain; the zone of animal
          or vegetable life in the ocean around an island or a
          continent; the Alpine zone, that part of mountains
          which is above the limit of tree growth.
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   5. (Crystallog.) A series of planes having mutually parallel
      intersections.
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   6. Circuit; circumference. [R.] --Milton.
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   7. (Biogeography) An area or part of a region characterized
      by uniform or similar animal and plant life; a life zone;
      as, Littoral zone, Austral zone, etc.

   Note: The zones, or life zones, commonly recognized for North
         America are Arctic, Hudsonian, Canadian, Transition,
         Upper Austral, Lower Austral, and Tropical.
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   8. (Cryst.) A series of faces whose intersection lines with
      each other are parallel.
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   9. (Railroad Econ.)
      (a) The aggregate of stations, in whatsoever direction or
          on whatsoever line of railroad, situated between
          certain maximum and minimum limits from a point at
          which a shipment of traffic originates.
      (b) Any circular or ring-shaped area within which the
          street-car companies make no differences of fare.
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   10. any area to or within which a shipment or transportation
       cost is constant; specifically, in the United States
       parcel-post system, any of the areas about any point of
       shipment for which but one rate of postage is charged for
       a parcel post shipment from that point. The rate
       increases from within outwards. The first zone includes
       the unit of area "(a quadrangle 30 minutes square)" in
       which the place of shipment is situated and the 8
       contiguous units; the outer limits of the second to the
       seventh zones, respectively, are approximately 150, 300,
       600, 1000, 1400, and 1800 miles from the point of
       shipment; the eighth zone includes all units of area
       outside the seventh zone.
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   Abyssal zone. (Phys. Geog.) See under Abyssal.

   Zone axis (Crystallog.), a straight line passing through
      the center of a crystal, to which all the planes of a
      given zone are parallel.
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Abyssal \A*byss"al\, a. [Cf. Abysmal.]
   Belonging to, or resembling, an abyss; unfathomable.
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   Abyssal zone (Phys. Geog.), one of the belts or zones into
      which Sir E. Forbes divides the bottom of the sea in
      describing its plants, animals, etc. It is the one
      furthest from the shore, embracing all beyond one hundred
      fathoms deep. Hence, abyssal animals, plants, etc.
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