The Collaborative International Dictionary of English v.0.48:

Grade \Grade\ (gr[=a]d), n. [F. grade, L. gradus step, pace,
   grade, from gradi to step, go. Cf. Congress, Degree,
   Gradus.]
   1. A step or degree in any series, rank, quality, order;
      relative position or standing; as, grades of military
      rank; crimes of every grade; grades of flour.
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            They also appointed and removed, at their own
            pleasure,
            teachers of every grade.              --Buckle.
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   2. In a railroad or highway:
      (a) The rate of ascent or descent; gradient; deviation
          from a level surface to an inclined plane; -- usually
          stated as so many feet per mile, or as one foot rise
          or fall in so many of horizontal distance; as, a heavy
          grade; a grade of twenty feet per mile, or of 1 in
          264.
      (b) A graded ascending, descending, or level portion of a
          road; a gradient.
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   3. (Stock Breeding) The result of crossing a native stock
      with some better breed. If the crossbreed have more than
      three fourths of the better blood, it is called high
      grade.
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   At grade, on the same level; -- said of the crossing of a
      railroad with another railroad or a highway, when they are
      on the same level at the point of crossing.

   Down grade, a descent, as on a graded railroad.

   Up grade, an ascent, as on a graded railroad.

   Equating for grades. See under Equate.

   Grade crossing, a crossing at grade.
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The Collaborative International Dictionary of English v.0.48:

Equate \E*quate"\, v. t. [imp. & p. p. Equated; p. pr. & vb.
   n. Equating.] [L. aequatus, p. p. of aequare to make level
   or equal, fr. aequus level, equal. See Equal.]
   To make equal; to reduce to an average; to make such an
   allowance or correction in as will reduce to a common
   standard of comparison; to reduce to mean time or motion; as,
   to equate payments; to equate lines of railroad for grades or
   curves; equated distances.
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         Palgrave gives both scrolle and scrowe and equates both
         to F[rench] rolle.                       --Skeat
                                                  (Etymol. Dict.
                                                  ).
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   Equating for grades (Railroad Engin.), adding to the
      measured distance one mile for each twenty feet of ascent.


   Equating for curves, adding half a mile for each 360
      degrees of curvature.
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