"Cossack commander," 1710, from Polish hetman, apparently from an early form of German Hauptmann "captain," literally "headman," from Haupt "head" (from PIE root *kaput- "head") + Mann (from PIE root *man- (1) "man").
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit manuh, Avestan manu-, Old Church Slavonic mozi, Russian muzh "man, male;" Old English man, mann "human being, person; brave man, hero; servant, vassal."
<a href="https://www.etymonline.com/word/hetman">Etymology of hetman by etymonline</a>
Harper, D. (n.d.). Etymology of hetman. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/hetman