Source : Webster's Revised Unabridged Dictionary (1913)

Spectroscopic \Spec`tro*scop"ic\, Spectroscopical
\Spec`tro*scop"ic*al\, a.
   Of or pertaining to a spectroscope, or spectroscopy. --
   {Spec`tro*scop"ic*al*ly}, adv.

Source : WordNet®

spectroscopical
     adj : of or relating to or involving spectroscopy; "spectroscospic
           analysis" [syn: {spectroscopic}]