The Collaborative International Dictionary of English v.0.48:

Capibara \Ca`pi*ba"ra\, n. (Zool.)
   See Capybara.
   [1913 Webster]

WordNet (r) 3.0 (2006):

capibara
    n 1: pig-sized tailless South American amphibious rodent with
         partly webbed feet; largest living rodent [syn: capybara,
         capibara, Hydrochoerus hydrochaeris]