The name Chasko is likely a truncation-suffix equivalent of the two-root name Chaslav. The oldest recorded form comes from the city of Lutsk and dates back to 1552: Chasko (Czasko) Martynovych (source: Archive of YUZR VI/1, page 179). From such names, patronymics also formed. For example, Kozak Trokhym Chaschenko from the Kalnytskyi regiment, who is mentioned in 1649 (source: RVZ, page 267).