Where does “陰イオン” come from?

陰イオン (Japanese) comes from Japanese イオン, from German ion, from English Ion, from Romanian Ion, from French ion, from English ion, from English anion, from Ancient Greek ἀνιόν — up, upon.

Ancestry of “陰イオン”, step by step

陰イオン traces back through two separate lines of ancestry.

via Japanese イオン

StepLanguageWordMeaning
1Japaneseイオンan ion
2Germanionion (an atom or group of atoms bearing an electrical charge)
3EnglishIonSon of Creusa and Xuthus, and the ancestor of Ionian people
4RomanianIonJohn
5Frenchionion
6EnglishionAn atom or group of atoms bearing an electrical...
7EnglishanionA negatively charged ion
8Ancient Greekἀνιόνgoing up
9Ancient Greekἄνειμιgo up
10Ancient Greekἀνάon board; on, upon
11Proto-Hellenic*anáup, upon

via Japanese

StepLanguageWordMeaning
1Japaneseshadow, shade; hidden side; yin
2Middle Chinese
Every word from Proto-Hellenic *anáEvery word from Ancient Greek ἀνάEvery word from Ancient Greek ἄνειμι