Barbarism is a language error where a non-standard or an incorrectly formed word or expression is used.
The word barbarism was originally used by the Greeks for foreign terms used in their language. As such, Anglicisms in other languages, Gallicisms (such as using the verb to assist to mean to be present at (cf. assister)), Germanisms, Hispanisms and so forth in English can also be construed as examples of barbarisms.
Note that a barbarism is an error of morphology, while a solecism is an error of syntax.
See also