Since 1962 Kuhn's concept of incommensurability has undergone a process of transformation. His current account of incommensurability has little in common with his original account of it. Originally, incommensurability was a relation of methodological, observational and conceptual disparity between paradigms. Later Kuhn restricted the notion to the semantical sphere and assimilated it to the indeterminacy of translation. Recently he has developed an account of it as localized translation failure between subsets of terms employed by theories.