Definitions of bilingualism are based on different, sometimes contradictory criteria, both in scientific and ordinary use of the term. Some of the criteria most often used in scientific work on bilingualism are compared to those used by the participants in research at the linguistic Institute in Neuchatel, Switzerland, as they are talking about…

True bilingualism is defined as having two mother tongues and a level of linguistic performance in both such that one is a full-fledged member of two linguistic communities. A survey of conference interpreters focuses on how one becomes a bilingual person and remains one, and what the advantages and disadvantages are. (MSE)