A retronym is a special compounding construction in the form of a noun with an unnecessary modifier, as in "paper book".It provides new evidence for language evolution,especially lexical semantic change. This paper explores the origin and compositions of the construction and, by focusing on prototype shift and split, makes an in-depth analysis of the complex interactions between the world, cognition and language. Our research shows: (1) as natural objects do not change abruptly, their categories tend to remain stable; (2) retronymy usually occurs in artificial object categories and it does so during the process of prototype shift; (3) the sub-categorization in relation to retronymy indicates an expansion of the whole category in question; (4) after a prototype shift in a category with its subcategories well rearranged and understood,a new prototype stability is reached and the retronymy dissolves; (5) therefore,diachronically,retronymy,which occurs only in a prototype shift, is not a permanent trait; and (6) retronymy provides a new window onto the fast development of modern science and technology and the evolution of human civilization.
