Where does “Ynysoedd y De” come from?

Ynysoedd y De (Welsh) comes from Welsh ynys, from Old Welsh inis, from Proto-Brythonic ɨnɨs, from Proto-Celtic enistī, from Proto-Indo-European h₁eni-sth₂-ih₂, from Proto-Indo-European steh₂- — to stand.

Ancestry of “Ynysoedd y De”, step by step

Ynysoedd y De traces back through 3 separate lines of ancestry.

via Welsh ynys

StepLanguageWordMeaning
1Welshynysisland; piece of land, realm, territory
2Old Welshinis
3Proto-Brythonicɨnɨsisland
4Proto-Celticenistīisland
5Proto-Indo-Europeanh₁eni-sth₂-ih₂
6Proto-Indo-Europeansteh₂-to stand

via Welsh y

StepLanguageWordMeaning
1Welshythe; that; which, whom
2Middle Welshyhis, its with reference to a masculine noun; triggers soft mutation of following consonant
3Old Welshirthe
4Proto-Celticsindosthis
5Proto-Indo-Europeansḗmone
6Proto-Indo-Europeansem-together, one

via Welsh de

StepLanguageWordMeaning
1Welshderight; south, southern; south
2Welshdeauright; south
3Proto-Celticdexswosright; south
4Proto-Indo-Europeandeḱswo-
5Proto-Indo-Europeandeḱs-right
Every word from Proto-Indo-European steh₂-
Ynysoedd y De — Etymology, Origin & Word History | Etymology Explorer