According to Grosjean’s (1989: 3–15) functionalist and holistic approach, the bilingual individual is not the sum of two monolinguals, but a specific “speaker-hearer”, forming a complete system, in which the two languages interact and complement each other. It is presumed that in the use of three or more languages, there is not only a quantitative but also a qualitative difference from bilingualism, and that it is therefore justified to separate bilingualism and multilingualism (Navracsics, 2004). On the other hand, research on bilingualism usually refers to two languages, but can sometimes include several languages (Bassetti, Cook, 2011). Multilingualism clearly refers to several languages, according to Aronin and Singleton (2008), and bilingualism is a special case of multilingualism. In this paper, I use multilingualism as a general term, including bilingualism. Multilingualism shows a higher level of complexity than bilingualism (Aronin, Jessner, 2015).