Abstract Old French noun inflection emerged and disappeared early in the history of the French language. A number or reasons are examined including the nature of sound changes occurring between Late Latin and Old French. Paradigm structure is another reason. The declensional paradigms of masculine nouns produced a mismatch between morphological and semantic defaults for the number and case features. This was because the non-default values of these features came to be expressed by a morphologically default, uninflected word-form, thus resulting in a system that was both weird in terms of the morphology-semantics interface and probably hard to acquire and to process. Repairing the mismatch entailed giving up declension in favour of a simple number contrast where the semantic non-defaultness of plurality matches the inflectedness of the plural form. Default considerations thus played the role of analogy in the Neogrammarian scenario of language change, restoring order where sound change had created chaos.

The article examines the grammatical features of the nominal parts of the French language, nouns, pronouns, and adjectives of the Middle Ages. An analysis of their morphological and syntactic evolution between the IXth and Vth centuries is carried out. The system of the nominal parts of speech in medieval French is distinguished by the presence of a system of two cases, inherited from Latin, which persisted until the 14th century and then gradually disappeared. This case system regulated the agreement of nouns, pronouns, and adjectives, indicating syntactic functions without the systematic use of prepositions. Research shows that the grammatical gender that already existed in Old French differed from modern French, as some nouns changed gender during the medieval period. The grammatical meaning of the singular was a subject to relatively stable agreement rules, while the morphology of the plural underwent significant changes. Medieval pronouns had greater morphological diversity than pronouns in modern French, with distinct case forms and a system of pronouns. Medieval adjectives agreed in case, gender, and number with the noun, and their syntactic position varied according to semantic and stylistic criteria. This diachronic analysis shows that the gradual simplification of the medieval system of the nominal parts of speech, especially the loss of the case system, profoundly restructured the French grammar, shifting the emphasis in syntax to the word order and the use of prepositions. These transformations are an important stage in the evolution of the French language to its modern form.