When two or more languages are mixed in the same utterance or text, the term “macaronic” is traditionally applied to such linguistic products, defined as being ‘characterized by a mixture of vernacular words jumbled together with Latin words or Latinized words or with words from one or more other foreign languages’ (Collins English Dictionary). A fuller, historically based definition is that of the Oxford English Dictionary Online: ‘Of or designating a burlesque form of verse in which vernacular words are introduced into the context of another language (originally and chiefly Latin), often with corresponding inflections and constructions; gen. of or designating any form of verse in which two or more languages are mingled together. Hence of language, style, etc.: resembling the mixed jargon of macaronic poetry.’
In the linguistic literature one can find terms such as “Japlish” or “Franglish” used to designate words that are of hybrid construction, drawing on a combination of English words or roots to form new Japanese or French vocabulary. A particularly striking example is that of contemporary Japanese discourse, especially as produced by younger speakers, which is often filled with such words––and even whole phrases and sentences in faux-English––enclosed in otherwise perfectly normal native contexts.
When it comes to French, a perfect example of the incidence of macaronic language presented itself yesterday when Y-H-B found himself seated next to two bilingual women (one in her twenties, the other in her forties or fifties) in a French restaurant on Lexington Avenue in Manhattan and could not avoid eavesdropping on their conversation, conducted in a potpourri of English and French. The younger of the two females, from whose utterances it transpired that she was raised in America in a French-speaking family, consistently interlarded her fluent Parisian French with long stretches of equally fluent, native American English (including uptalk and ticastic like), to which her older interlocutor always responded exclusively in French. It became clear that the younger woman (a computer programmer, as it turned out) was incapable of expressing herself in French to the same degree as English and consequently resorted to fast-paced English sentences and sentence fragments, alternating with French framing sentences. This macaronic mélange, inescapably within Y-H-B’s earshot, was most definitely not on the menu and caused great annoyance to the sensibility of a dyed-in-the-wool prescriptivist and purist, who recognized (and appreciated malgré lui) the perfection of the young woman’s speech as a rare example of the genre.
[ADDENDUM. Anent the etymology of ‘macaronic’, here is information from the Encyclopaedia Britannica: “Teofilo Folengo,