The article provides a phonetic and areal analysis of stems with the meaning ‘melted, unfrozen' attested in the toponymy of the Russian North and adjacent districts of Kostroma region. The empirical basis of the study is constituted by names of both Russian and substrate origin recorded in the fi les of the Ural University Toponymic Expedition, as well as by Veps, Karelian and Finnish toponyms taken into consideration as comparative material. When analysing the stems of Finnic and Sami origin with the meaning ‘melted, unfrozen' as attested in the substrate toponymy of the Russian North, the author proposes an interpretation of their phonetic variation and areal distribution and specifi es the etymological explanation of place names with the stems Shund- and Sond-. The investigation into the Russian word family of talyi ‘melted (ice, snow)' shows that the stems belonging to this family are far from being typical for the Russian toponymy of the region, appearing mainly
in landscape terms talets, talik and talitsa. As to the adjective talyi itself, it is also of rare use in the studied toponymy — the analysis of the geographical distribution of such names (present chiefl y in the northwestern part of the studied area) and of comparable substrate forms shows that,
for the most part, they represent adaptations of homonymic substrate names or, as in some instances, loan translations.