The present paper deals with the attrition of the first language. It presents a general overview of language attrition as a research field and discusses the main characteristics of the phenomenon by examining some typical lexical, grammatical, and phonological properties of attriters’ speech. Our attention is drawn here to a variety of factors, such as age, time spent in the L2 environment, frequency of first language use, language attitudes, and other aspects that have an impact on language attrition. The paper also reflects on and motivates the choice of the term ‘attrition’ in the Lithuanian academic use. The current empirical analysis focuses on an extreme case of first language attrition in the situation of international adoption of an...