Where does “лекост” come from?

лекост (Bulgarian) comes from Bulgarian лек, from Proto-Slavic lьgъkъ, from Proto-Indo-European h₁lengʷʰ- — light.

Ancestry of “лекост”, step by step

StepLanguageWordMeaning
1Bulgarianлекlight; easy, effortless, facile, simple, soft,...
2Proto-Slaviclьgъkъlight
3Proto-Indo-Europeanh₁lengʷʰ-light
Every word from Proto-Indo-European h₁lengʷʰ- →
лекост — Etymology, Origin & Word History | Etymology Explorer