Where does “тепло-” come from?

тепло- (Russian) comes from Ukrainian те́плий, from Proto-Slavic teplъ, from Proto-Indo-European tep- — to be warm, be hot.

Ancestry of “тепло-”, step by step

StepLanguageWordMeaning
1Ukrainianте́плийwarm
2Proto-Slavicteplъwarm
3Proto-Indo-Europeantep-to be warm, be hot
Every word from Proto-Indo-European tep- →Every word from Proto-Slavic teplъ →Every word from Ukrainian те́плий →