The Collaborative International Dictionary of English v.0.48:

Ethology \E*thol"o*gy\, n. [Gr. ? a depicting of character; ?
   custom, moral nature + ? to speak.]
   1. A treatise on morality; ethics.
      [1913 Webster]

   2. The science of the formation of character, national and
      collective as well as individual. --J. S. Mill.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ethology
    n 1: the branch of zoology that studies the behavior of animals
         in their natural habitats