The story
- Proto-Indo-European*swé
- Proto-Indo-European*dʰeh₁-
- Proto-Indo-European*swe-dʰh₁-
- Proto-Hellenic*séswōtʰa
- Ancient Greekἔθω (éthō)
- Ancient Greekἔθνος (éthnos)
- Ancient Greekἐθνικός (ethnikós)
- Latinethnicus
- Middle Englishethnik
- English todayethnic
From Middle English ethnik, from Latin ethnicus ("pagan", "heathen"), from Ancient Greek ἐθνικός (ethnikós, “of or for a nation, heathen”), from ἔθνος (éthnos, “a company", later "a people or nation, heathens”). By surface analysis, ethno- + -ic.
Etymology from Wiktionary, CC BY-SA 4.0.