Cosack or Cossack: How To spell?
The word Cosack is misspelled against Cossack, a noun meaning "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."
Cossack has double "ss" is mispronounced as "s"Remember double 'SS' in between the strings co & ack which should not be misspelled with single 'S'
Wrong Spelling:  co-s-ack  Correct Spelling:  co-ss-ack 
Find more incorrect spellings of Cossack to spell right way.