The Collaborative International Dictionary of English v.0.48:

Guib \Guib\, n. (Zool.)
   A West African antelope (Tragelaphus scriptus), curiously
   marked with white stripes and spots on a reddish fawn ground,
   and hence called harnessed antelope; -- called also
   guiba.
   [1913 Webster]

WordNet (r) 3.0 (2006):

guib
    n 1: antelope with white markings like a harness and twisted
         horns [syn: bushbuck, guib, Tragelaphus scriptus]