Latin word somnium comes from Proto-Indo-European *seup-, Proto-Indo-European - nós

Detailed word origin of somnium

Dictionary entry	Language	Definition
*seup-	Proto-Indo-European (ine-pro)
- nós	Proto-Indo-European (ine-pro)
*swopnos	Proto-Indo-European (ine-pro)
*swópniyom	Proto-Indo-European (ine-pro)
*swepnos	Proto-Italic (itc-pro)
somnium	Latin (lat)	Dream, vision. Fantasy, daydream.