Along with the neighbouring Lemkos and Hutsuls, the Boykos are considered a sub-group of Rusyns and speak a distinct East Slavic dialect.

Regarding the origin of the name Boyko there exist several etymological hypotheses,[6] but it is generally considered, as explained by priest Joseph Levytsky in his Hramatyka (1831), that it derives from the particle boiie.

[8] The 19th-century scholar Pavel Jozef Šafárik, with whom Franjo Rački and Henry Hoyle Howorth agreed, argued a direct connection of the Boykos with the region of Boiki mentioned in the 10th century De Administrando Imperio,[7][9] but this thesis is outdated and rejected,[8] as most scholars, Mykhailo Hrushevsky among them, already dismissed it in the 19th century because Boiki is a clear reference to Bohemia, which in turn derives from the Celtic tribe of Boii.

[19][20][21] The deprecated and archaic term Ruthenian, while also derived from Rus', is ambiguous, as it technically may refer to Rusyns and Ukrainians, as well as Belarusians and in some cases Russians, depending on the historical period.

[2] To the west of Boykos live Lemkos, east or southeast Hutsuls, northward Dnistrovyans, Opolyans.