This paper discusses the definitions of the terms ergative, absolutive, accusative and nominative (as general concepts), which are often taken for granted in the literature. Several authors, notably Mel’čuk and Creissels, have criticized some of the terminological usage, but I note here that the classical definitions (in terms of alignments of S, A and P) need not be modified. The crucial point to keep in mind is that language-particular descriptive categories are distinct from comparative concepts for general linguistics.