A more common term for the phenomenon is 'passive bilingualism'.
François Grosjean argues that there has been a monolingual bias regarding who is considered a 'bilingual' in which people who do not have equal competence in all their languages are judged as not speaking properly. 'Balanced bilinguals' are, in fact, very rare. One's fluency as a bilingual in a language is domain-specific: it depends on what each language is used for. That means that speakers may not admit to their fluency in their passive language although there are social (extralinguistic) factors that underlie their different competencies. == See also ==