Where does “søsken” come from?
søsken (Norwegian Bokmål) comes from Old Norse systkin, from Old Norse systir, from Proto-Norse ᛊᚹᛖᛊᛏᚨᚱ, from Proto-Germanic swestēr, from Proto-Indo-European swésōr, from Proto-Indo-European su-h₁ésh₂-ōr, from Proto-Indo-European h₁ésh₂r̥ — blood.
søsken (Norwegian Bokmål): a sibling
Ancestry of “søsken”, step by step