Source : Webster's Revised Unabridged Dictionary (1913)

Etymology \Et`y*mol"o*gy\ (-j[y^]), n.; pl. {Etymologies}
   (-j[i^]z). [L. etymologia, Gr. 'etymologi`a; 'e`tymon etymon
   + lo`gos discourse, description: cf. F. ['e]tymologie. See
   {Etymon}, and {-logy}.]
   1. That branch of philological science which treats of the
      history of words, tracing out their origin, primitive
      significance, and changes of form and meaning.

   2. That part of grammar which relates to the changes in the
      form of the words in a language; inflection.

Source : WordNet®

etymology
     n 1: a history of a word
     2: the study of the sources and development of words