Where does “кашлянуть” come from?
кашлянуть (Russian) comes from Russian ка́шлять, from Proto-Slavic kašьľati, from Proto-Slavic kaš(ь)ľь, from Proto-Balto-Slavic kāˀsulia, from Proto-Balto-Slavic kāˀs-, from Proto-Indo-European kʷeh₂s- — to cough.
кашлянуть (Russian): to cough
Ancestry of “кашлянуть”, step by step