A separate language unique to an ethnonational group has significant role to play in an ethnonational movement and/or conflict. The language can be a symbol of the separate identity of the group. The language can be an important issue of the movement or conflict when it is excluded from the status of an official language. If there is a certain objective criterion by which the separateness of a language can be determined, then the task of those interested in the function of language in ethnonational conflicts will be to explore how the language is used for political purpose. There is, however, no such handy criterion. The identification and differentiation of languages are often made on non-linguistic, political grounds. The present paper attempts, as a first step, to clarify the ways or patterns of identification and differentiation of languages. It provides a basis for better understanding of how a “separate" language is produced and is exploited for political purposes, especially for ethnonational purposes.