Charles Stevenson introduced the term \u27persuasive definition\u27 to describe a suspect form of moral argument \u27which gives a new conceptual meaning to a familiar word without substantially changing its emotive meaning\u27. However, as Stevenson acknowledges, such a move can be employed legitimately. If persuasive definition is to be a useful notion, we shall need a criterion for identifying specifically illegitimate usage. I criticize a recent proposed criterion from Keith Burgess-Jackson and offer an alternative