The word 'Yiddish' entered English in the late 19th century from the German term 'jüdisch', meaning 'Jewish'. This German adjective itself derives from 'Jude' (Jew), which traces back through Old High German 'judeo' to Latin 'Iudaeus' and ultimately Greek 'Ioudaios', referring to a person from the ancient kingdom of Judah. The linguistic journey encapsulates a shift from a general ethnic and religious identifier ('Jewish') to the specific name for the unique High German-derived language of the Ashkenazim. Thus, the term's logic lies in its origin as the word for "Jewish" in the language that forms its core, signifying the "Jewish (language)" of Central and Eastern Europe.

The word is a loanword from English into which it came as a simplex. Its components are not productively separable in modern English spelling. It originates from the German word 'jüdisch', meaning 'Jewish'.