Russian word сложный comes from Proto-Indo-European *logʰéyeti, and later Proto-Slavic *ložiti (To lay.)

Detailed word origin of сложный

Dictionary entry	Language	Definition
*logʰéyeti	Proto-Indo-European (ine-pro)
*ložiti	Proto-Slavic (sla-pro)	To lay.
сложный	Russian (rus)	Complex, compound. Complicated, intricate.

Words with the same origin as сложный