Of course when I use the term "inexorable," I do not mean that the world and our language could not have been otherwise; the word "bird" could have referred to frogs instead of pelicans, or to only puffins, robins, and sparrows, but not pelicans, ostriches, and condors. Definitions are contingent and subject to change, and therefore the word "bird" might yet come to be the word that speakers of English use to refer to frogs, or only to small and not to large birds. Yet although there remains a possibility that the word "bird" will come to mean these things, this is only a possible world-it is not our world. In our world, the exclusion of frogs and the inclusion of large birds is definitionally part of the meaning of the word "bird." As I argue below, see infra notes 56-57 and accompanying text, the contingency of definition hardly entails the view that it is within the province of any one actor, legal or otherwise, to change it. Neither you nor I have the power to make it proper to use the word "bird" to refer to a frog, even though the word "bird" could in another world be used to refer to frogs.

DEFINE: Clarifies the distinction between a definition being contingent (could have been otherwise in another possible world) and it being within anyone's power to alter it in our world.

Frederick Schauer, Frederick Schauer - Formali…, loc. 26