Where does “undern-song” come from?

undern-song (English) comes from Old English undernsang, from Old English undern, from Proto-Germanic undurniz, from Proto-Indo-European h₁n̥ter.

Ancestry of “undern-song”, step by step

StepLanguageWordMeaning
1Old Englishundernsangterce
2Old Englishundernterce, the third hour of the day; midday, the...
3Proto-Germanicundurnizan intermediate or intervening period; mean time;...
4Proto-Indo-Europeanh₁n̥ter
Every word from Proto-Indo-European h₁n̥terEvery word from Proto-Germanic undurnizEvery word from Old English undern