'Cossack' definitions:
Definition of 'Cossack'
(from WordNet)
noun
A member of a Slavic people living in southern European Russia and Ukraine and adjacent parts of Asia and noted for their horsemanship and military skill; they formed an elite cavalry corps in czarist Russia
Definition of 'Cossack'
From: GCIDE
- Cossack \Cos"sack\ (k?s"s?k), n. [Russ. kozak', kazak': cf. Turk. kaz[=a]k.] One of a warlike, pastoral people, skillful as horsemen, inhabiting different parts of the Russian empire and furnishing valuable contingents of irregular cavalry to its armies, those of Little Russia and those of the Don forming the principal divisions. [1913 Webster]