Source : Webster's Revised Unabridged Dictionary (1913)

Trigonometric \Trig`o*no*met"ric\, Trigonometrical
\Trig`o*no*met"ric*al\, [Cf. F. trigonom['e]trique.]
   Of or pertaining to trigonometry; performed by the rules of
   trigonometry. --{Trig`o*no*met"ric*al*ly}, adv.

   {Trigonometrical curve}, a curve one of whose co["o]rdinates
      is a trigonometric function of the other.

   {Trigonometrical function}. See under {Function}.

   {Trigonometrical lines}, lines which are employed in solving
      the different cases of plane and spherical trigonometry,
      as sines, tangents, secants, and the like. These lines, or
      the lengths of them, are trigonometrical functions of the
      arcs and angles to which they belong.

   {Trigonometrical survey}. See under {Survey}.

Source : WordNet®

trigonometric
     adj : of or relating to or according to the principles of
           trigonometry; "trigonometric function"