The studies on lexicographic definitions connected with the French tradition take charge eminently of typology and leave aside the question of metalanguage. So, in lexicography, the metalinguistic definition is often considered in the typological frame. This is because the above-mentioned studies are mostly based upon definitions either of nouns or verbs. In my presentation I shall attempt to demonstrate, from defining statements of the syncategorematic words drawn from the Tresor de la langue francaise, that the metalinguistic definition is indeed a category of the definitions but that, when compared to the other categories, it requires a different criteria of analysi, due to its nature. In order to do this, I shall present, first, the different nature of this issue from a typological approach on one side and a metalinguistic approach on the other. I shall expose, then, the main typological studies-in particular the unpublished document which is stored in the archives of the Laboratory ATILF [.Pour un nouveau cahier de normes...., 1979] as well as Martin (1983) and Rey-Debove (1998)-in which the question of the metalanguage is dealt with inside and following the example of typology to demonstrate that, if a definition such as aiguillette-nom populaire de l.orphie-is metalinguistic and a definition such as chaise - siege a dossier sans bras - is perifrastic, nom et siege are both hyperonyms, so that the typological criteria are not enough to distinguish between mealinguistic and perifrastic definition. Thus, I will establish, in accordance with Rey-Debove (1997), in which the definition is considered from a metalinguistic point of view-according to the sintactic relation between a lexical entry and its lexicographical definition, the principles which govern the metalinguistic analysis. The results will lead to three different categories of metalinguistic definitions of the syncategorematic words: 1. the definition refers to both infralinguistic and extralinguistic reality-in this case two sub-categories are possible: a) the hyperonym refers to the infralinguistic reality while the specific semes refer to the extralinguistic reality; b) the hyperonym refers to the infralinguistic reality while the specific semes, among which there is at least an autonym with 'schize' (cf. Rey-Debove 1997: 116-118), refer to the extralinguistic reality; 2. the definition refers to the only infralinguistic reality; 3. the definition refers to the only extralinguistic reality.