Tetragonal \Te*trag"o*nal\, a.
   1. (Geom.) Of or pertaining to a tetragon; having four angles
      or sides; thus, the square, the parallelogram, the
      rhombus, and the trapezium are tetragonal fingers.
      
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   2. (Bot.) Having four prominent longitudinal angles.
      
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   3. (Crystallog.) Designating, or belonging to, a certain
      system of crystallization; dimetric. See {Tetragonal  system}, under {Crystallization}.
      
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