Care should be taken to differentiate these two uses of the term:
- Langue d'oïl is an Old French term meaning language of oïl. Modern-day languages of this family are also referred to in English as Oïl languages. Since the latter half of the 20th century the tendency in French has been to refer to the languages in the plural as langues d'oïl to clearly distinguish one language taken in isolation or the linguistic grouping as a whole.
- The term langue d'oïl is also used in a historical sense to refer to Old French, which was distinguished from another Gallo-Romance variety, the langue d'oc, by the word meaning "yes" in those languages. Vulgar Latin developed diffent methods of signifying assent: hoc ille for Langue d'oil and hoc for Langue d'oc. the subsequent development of "oïl" into "oui" can be seen in modern French.
Although the competing literary standards of the Oïl languages in the mediaeval period might have developed into a situation where each language retained its status within the territory where it was spoken, the centralisation of the French kingdom and its influence even outside its formal borders had the effect of sending most of the Oïl languages into comparative obscurity for several centuries.
Two main theories tend to be put forward to explain the rise of French language:
The Francien theory
It is claimed that Francien, the Oïl language of the Paris region and therefore of the French court, was simply imposed as official language in all the territory of the kingdom because it was the language the king spoke. This Francien became the modern French language.
Current linguistic thinking mostly discounts the Francien theory, although it is still often quoted in popular textbooks.
The Lingua franca theory
Most linguists working in the field tend to advance variations on the theory that the "French" language, imposed by the Ordinance of Villers-Cotterêts to replace Latin, was not a particular variety of Oïl language, but rather a generalised administrative language, shorn of distinguishing regional features and equally comprehensible to all - a lingua franca.
It is argued that this language was not intended to become a national language, merely a chancery language for law and administration. However, the development of literature in this new language encouraged writers to use French rather than their own regional languages. this led to the decline of vernacular literature.
Until the First World War, French was not primarily the language of the French people - the regional languages of France were still the languages most used in the home and in the fields. Thus was also generally the case with the Oïl languages.
Besides the influence of French literature, small-scale literature has survived in the other Oïl languages. Theatrical writing is most notable in Picard and Poitevin-Saintongeais. Oral performance (story-telling) is a feature of Gallo, for example, while Norman and Walloon literature, especially from the early 19th century tends to focus on written texts and poetry.
Apart from French, an official language in many countries, the Oïl languages have enjoyed little status.
Currently Walloon, Lorrain (under the local name of Gaumais) and Champenois have the status of regional languages of Wallonia.
The languages of the Channel Islands enjoy a certain status under the governments of their respective Bailiwicks and within the regional and lesser-used language framework of the British-Irish Council.
The French government recognises the Oïl languages as Languages of France but has been constitutionally barred from ratifying the European Charter for Regional or Minority Languages.
The French spoken in Belgium shows some influence from Walloon.
The development of French in North America was influenced by the speech of settlers originating from north-western France, many of whom introduced features of their Oïl varieties into the French they spoke.
This list follows the Francien theory, as explained above.
- Gallo language (spoken in Brittany)