The morphemes such as the French au or the Italien nel are designed by different terms in
grammars of Romance languages, which shows that it is difficult to identify the lexical category of this type of fusional
morpheme. The aim of this paper is to propose a detailed analysis of these contracted forms. I suggest that the fusion occurs
during a secondary grammaticalization. This process involves, on the one hand, the definite article, i.e. a grammatical element,
and, on the other hand, some prepositions which, semantically, can be functional or lexical but which function syntactically as
grammatical elements. The analysis shows that case inflection of nominals has been transferred to the preposition while the other
categories appear in the article which merged with prepositions. Therefore, the fusional forms can be considered as prepositions
marked by the grammatical categories of gender, number and definiteness.