The Collaborative International Dictionary of English v.0.48:

Ethnology \Eth*nol"o*gy\n. [Gr. ? nation + -logy.]
   The science which treats of the division of mankind into
   races, their origin, distribution, and relations, and the
   peculiarities which characterize them. Ethologic

WordNet (r) 3.0 (2006):

ethnology
    n 1: the branch of anthropology that deals with the division of
         humankind into races and with their origins and
         distribution and distinctive characteristics

The Devil's Dictionary (1881-1906):

ETHNOLOGY, n.  The science that treats of the various tribes of Man,
as robbers, thieves, swindlers, dunces, lunatics, idiots and
ethnologists.