The Collaborative International Dictionary of English v.0.48:

Diophantine \Di`o*phan"tine\, a.
   Originated or taught by Diophantus, the Greek writer on
   algebra.
   [1913 Webster]

   Diophantine analysis (Alg.), that branch of indeterminate
      analysis which has for its object the discovery of
      rational values that satisfy given equations containing
      squares or cubes; as, for example, to find values of x and
      y which make x^2 + y^2 an exact square.
      [1913 Webster]