Eysteinn (Old Norse) comes from Old Norse steinn, from Proto-Norse ᛊᛏᚨᛁᚾᚨᛉ, from Proto-Germanic stainaz, from Proto-Indo-European steyh₂-, from Proto-Indo-European steh₂- — to stand.
Ancestry of “Eysteinn”, step by step
Eysteinn traces back through two separate lines of ancestry.