Voisko

A Cossack host (Ukrainian: Козаче військо, kozache viysko; Russian: каза́чье во́йско, kazachye voysko), sometimes translated as Cossack army, was an administrative subdivision of Cossacks in the Russian Empire. The word host is an archaic word for army.

The Cossack host consisted of a certain territory with Cossack settlements that had to provide military regiments for service in the Imperial Russian Army and for border patrol. Usually the hosts were named after the regions of their dislocation. The stanitsa, or village, formed the primary unit of this organization.

In the Russian Empire, the Cossacks constituted eleven separate hosts, settled along the frontiers: the Don, Kuban, Terek, Astrakhan, Ural, Orenburg, Siberian, Semiryeche, Transbaikal, Amur, and Ussuri.

There was also a small number of the Cossacks in Krasnoyarsk and Irkutsk, who would form the Yenisey Cossack Host and Irkutsk Cossack Regiment of the Ministry of the Interior in 1917.

...
Wikipedia