We aim in this search to define the significations of N (name) fois through the main constructions using it in modern French, and to explain how it helped in forming the derived expressions autrefois, des fois (que), parfois, quelquefois, toutefois, une fois (que). From a lexical point of view, the word fois is a feminine substantive, and, built with a determiner, it forms a nominal group (NG). The N fois denotes an occurrences counting, that means discurse units counting, mostly verbal process or predicates. Therefore it concerns liunguistic units and that's why fois is used in several contexts. We organized the main constructions according to the determiner used in NG fois. Firstly, NG built with cardinal adjectives or quantifiers + fois allow counting language occurrences and function as a quantification adverb ; if the occurrences are verbal process, they bring besides a temporal notion with iterative or frequential value. With other déterminers (definite and indefinite article, demonstrative adjective, universal quantifiers tous les and chaque), fois is a temporal name on the way to standardisation. The derived expressions change semantically and come to an adverbial form prior other transformations. This concludes to identify the group of quantification adverbs, the former one, which helped the formation of derived expressions, and a newer group in which fois is a temporal name as jour, instant or moment.
