standard gauge
    n 1: railroad track having the standard width of 56.5 inches

Standard \Stand"ard\, a.
   1. Being, affording, or according with, a standard for
      comparison and judgment; as, standard time; standard
      weights and measures; a standard authority as to nautical
      terms; standard gold or silver.
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   2. Hence: Having a recognized and permanent value; as,
      standard works in history; standard authors.
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   3. (Hort.)
      (a) Not supported by, or fastened to, a wall; as, standard
          fruit trees.
      (b) Not of the dwarf kind; as, a standard pear tree.
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   Standard candle, Standard gauge. See under Candle, and
      Gauge.

   Standard solution. (Chem.) See Standardized solution,
      under Solution.
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