Trademark names constitute a mixed category, which doesn't fit in the traditional distinction between proper names and common names. This paper would show that the hybrid semiotics of trademark names relate them to proper names, common names or terms, without owing one or other of the characteristic properties of these. The author successively considers syntactic, referential, semantic and legal properties of trademark names. With their structural diversity square a semiotic heterogeneity which constitutes this category as a stumbling block of the lexical reflexion.