Many linguists frame this change in heritage language acquisition as “incomplete acquisition” or "attrition." "Incomplete acquisition," loosely defined by Montrul, is "the outcome of language acquisition that is not complete in childhood." In this incomplete acquisition, there are particular properties of the language that were not able to reach age-appropriate levels of proficiency after the dominant language has been introduced. Attrition, as defined by Montrul, is the loss of a certain property of a language after one has already mastered it with native-speaker level accuracy. These two cases of language loss have been used by Montrul and many other linguists to describe the change in heritage language acquisition. However, this is not the only viewpoint of linguists to describe heritage language acquisition.