Where does “hiærnæ” come from?

hiærnæ (Old Danish) comes from Old Norse hjarni, from Proto-Germanic hersô, from Proto-Indo-European ḱerh₂s-, from Proto-Indo-European ḱerh₂- — head, top; horn.

Ancestry of “hiærnæ”, step by step

StepLanguageWordMeaning
1Old Norsehjarnithe brain
2Proto-Germanichersôcrown of head
3Proto-Indo-Europeanḱerh₂s-head; hornet
4Proto-Indo-Europeanḱerh₂-head, top; horn
Every word from Proto-Indo-European ḱerh₂- →Every word from Proto-Indo-European ḱerh₂s- →Every word from Proto-Germanic hersô →
hiærnæ — Etymology, Origin & Word History | Etymology Explorer