Are conversion, selectivity and yield terms unambiguously defined in chemical and chemical engineering terminology?

This review shows and discuss the different definitions and use of conversion, selectivity and yield, with reference both to different reactor types and reaction schemes. Books or manuscripts focusing on kinetics prefer to express selectivity as the amount of the product desired weighted with respect to all the possible by-products. This definition may come directly from the comparison of the reaction rates bringing to the different species. By contrast, authors devoted to process or reactor design prefer a more practical definition of selectivity as amount of product formed with respect to what have reacted.