Individual Bilingualism (or Multilingualism)
Multilingualism usually refers to a speakerís knowledge and efficient use of three or more languages while bilingualism is the sociolinguist's term to describe a speakerís knowledge and use of more than one, i.e. two, languages - their mother tongue and an additional language. However, multilingualism and bilingualism are often used interchangeably and bilingualism might also indicate that a speaker knows and uses more than two languages. Thus, bilingualism means the mastering of two or more languages.
A communicatively competent multilingual speaker is able to code-switch between the varieties he or she knows and uses in accordance with the demands of different social situations.
A communicatively competent multilingual speaker has both active and passive knowledge of the language varieties he or she uses. In other words, this speaker can understand (= passive knowledge) certain varieties in the speech and writing of others and he or she can actively use his or her own speech or writing abilities in the respective varieties (= active knowledge). However, multilingual speakers often do not have identical competence in all the languages they know.
The opposite of multilingualism is monolingualism which describes a speaker who knows and uses one language only Ė his or her native language.
A person with monolingual competence is called a monolingual. A person with multilingual/bilingual competence is called a multilingual or bilingual.
Bilinguals can be further distinguished into coordinate bilinguals and compound bilinguals. Coordinate and compound bilingualism illustrate how the different social conditions under which speakers become bilingual can lead to differences in how these speakers relate words to their meanings. In this connection, coordinate bilingualism refers to individuals who speak two languages natively, i.e. they have learned both languages from birth, while compound bilingualism describes individuals who have learned one language natively and another one later in their life.
Summing up, the terms multilingualism and bilingualism refer to the language competence of the individual language user. In this case we speak of individual bilingualism (or: multilingualism).
Individual bilingualism is distinguished from societal bilingualism (or: multilingualism).