Mandaeism

The story

1. Ancient Greek · derived from-ισμός
2. Aramaic · derived from𐡌𐡍𐡃𐡏“knowledge”
3. English todayMandaeism

From Aramaic 𐡌𐡍𐡃𐡏 (manda, “knowledge”) + -ism (from Ancient Greek -ισμός (-ismós)). Although Mandaeism is the most widespread spelling in English, it is a hypercorrection. The expected derivation through Greek Μανδαϊσμός (Mandaïsmós) and Latin Mandaismus is Mandaism (compare with Judaism, from Ancient Greek Ἰουδαϊσμός (Ioudaïsmós), or with archaism, from Ancient Greek ἀρχαϊσμός (arkhaïsmós)).