Marollian (; ) is a traditional dialect native to Brussels, Belgium, sometimes considered by some speakers and linguists as a distinct variety of Brusselian. A mixture of French, Picard and Flemish Brusselian, it was widely spoken in the Marolles/Marollen neighbourhood of the City of Brussels, from which it takes its name, until the 20th century. It still survives among a small minority of inhabitants called Brusseleers (or Brusseleirs), many of them quite bi- and multilingual in French and Dutch.
The toponyms ' in Dutch or ' in French refer to the Marolles/Marollen, a neighbourhood of the City of Brussels, near the Palace of Justice, which itself takes its name from the former abbey of the Apostoline sisters, a religious group based in this area during the Middle Ages (from in Latin ("those who honour the Virgin Mary"), later contracted to /, and finally /). Historically a working class neighbourhood, it has subsequently become a fashionable part of the city.
There is a dispute and confusion about the meaning of Marollian, which many consider to be a neighbourhood jargon distinct from a larger Brusselian dialect, while others use the term as an overarching substitute for that citywide dialect. It is a triple language based on a mixture of French and Picard, incorporating vocabulary and expressions from Flemish Brusselian. According to Jeanine Treffers-Daller, "the dialect has a tremendous prestige and a lot of myths are doing the rounds."
Marollian is described as "totally indecipherable to the foreigner (which covers everyone not born in the Marolles), which is probably a good thing as it is richly abusive."