Source : Webster's Revised Unabridged Dictionary (1913)

Subtriplicate \Sub*trip"li*cate\, a. (Math.)
   Expressed by the cube root; -- said especially of ratios.

   {Subtriplicate ratio}, the ratio of the cube root; thus, the
      subtriplicate ratio of a to b is [cuberoot]a to
      [cuberoot]b, or [cuberoot]a/b.