The masculine name Mysko is mentioned several times in the Registers of the Zaporizhian Army from 1649. In particular, there is the Cossack of the Poltava Regiment, Mysko Olkhovych; Cossacks of the Mirgorod Regiment, Mysko Mamchenko and Mysko Pavlovych; Cossacks of the Kropyvnyansky Regiment, Mysko Buryak and Mysko Chorny; the Cossack of the Uman Regiment, Mysko Chorny’s son; and the Cossack of the Bratslav Regiment, Mysko Lyakh (R.V.Z 248, 386, 391, 358, 362). The name is also mentioned in the Kharkiv Census of 1660: Cossack Mysko Omelchenko (H.P. 164). The name Mysko is likely a shortened version of the ancient Hebrew personal name Misael, although it can also be derived from some Slavic compound name containing the root - MYSL - for example, Dobromysl.