Where does “Jilek” come from?

Jilek (English) comes from Czech Jílek, from Czech jíl, from Old Czech jíl, from Proto-Slavic jьlъ, from Proto-Slavic jìlъ, from Proto-Balto-Slavic ī́ˀlus, from Proto-Indo-European (H)iHlús — mud; dark.

Ancestry of “Jilek”, step by step

StepLanguageWordMeaning
1CzechJílekryegrass any of several species of tufted grasses of the genus
2Czechjílclay
3Old Czechjílclay
4Proto-Slavicjьlъsilt; clay
5Proto-Slavicjìlъ—
6Proto-Balto-Slavicī́ˀlus—
7Proto-Indo-European(H)iHlúsmud; dark
Every word from Proto-Indo-European (H)iHlús →Every word from Proto-Balto-Slavic ī́ˀlus →Every word from Proto-Slavic jìlъ →