Where does “ondern” come from?

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

Ancestry of “ondern”, step by step

StepLanguageWordMeaning
1Old Englishundernterce, the third hour of the day; midday, the...
2Proto-Germanicundurnizan intermediate or intervening period; mean time;...
3Proto-Indo-Europeanh₁n̥ter—
Every word from Proto-Indo-European h₁n̥ter →Every word from Proto-Germanic undurniz →Every word from Old English undern →