Source : Webster's Revised Unabridged Dictionary (1913)

Etymological \Et`y*mo*log"ic*al\ (-m[-o]*l[o^]j"[i^]*kal), a.
   [L. etymologicus, Gr. 'etymologiko`s: cf. F. ['e]tymologique.
   See {Etymology}.]
   Pertaining to etymology, or the derivation of words. --
   {Et`y*mo*log"ic*al*ly}, adv.

Source : WordNet®

etymological
     adj : based on or belonging to etymology; "I merely drew an
           etymological distinction"