The aim of this study is to examine the different approaches to the definition of bilingualism and those who are considered to be bilinguals and to create a conceptual framework for the researchers working in this field. For this purpose, a literature review was conducted, the books and articles of the prominent researchers in this field were examined, and differences of opinion were determined and evaluated. Since bilingualism can be defined depending on many variables, such as age, way of acquisition, acquisition conditions, the status of the mother tongue, the level of competence in both languages, there exist different opinions concerning the definition of this concept. The term "bilingualism" is a highly complex social, psychological, and linguistic phenomenon, commonly used to describe individuals who have acquired the ability to use two different languages. While some linguists argue that an individual should have equal competences in both languages in order to be called bilingual, the others stand against this point of view and maintain that being able to speak both languages impeccably is not an indispensable condition of bilinguality. Alongside with those researchers who indicate that in order to be called a bilingual one should acquire the second language before the critical period, there are those who consider people that have learnt a foreign language in adulthood also as bilinguals. According to some researchers, bilingualism is not the sum of two monolingual speakers; it is also closely related to cultural identity. Bilingualism is the ability to use both languages alternately and as an alternative to each other.
Bilingualism, bilingual, type of bilingualism, advantages and disadvantages of bilingualism.