Recent improvements in information technologies, together with the social and economic changes affecting societies and the world of work today, make it necessary for the French higher education sector to consider the teaching practices of specialised languages (or LSPs) as a particular form of transdisciplinarity. Based on the exploratory survey of open-ended questionnaires, the present contribution aims to define the notion of « borrowed knowledge » characterising the teachers of specialised languages' expert knowledge by analysing the French higher education context and its evolution of teaching practices since the 1970s. After giving a general overview of such a context in Part One, Part Two discusses the theoretical foundation of the construct of « borrowed knowledge » and its operative dimension. Part Three will then describe, analyse and discuss the qualitative exploration of teaching practices in LSP and its didactic make-up explored in a questionnaire survey conducted in two French universities. It combines a discussion about didactic expertise in language teaching and its links with transdiciplinarity, taking language biographies into account.