Many people believe that words have fixed meanings, the sorts of things we can find in a dictionary. For example, to them a word like ‘bachelor’ means ‘unmarried male’ and that’s the end of the matter. We can see how this theory can influence educational practice. The idea that words have fixed meanings would imply we can teach word meaning by giving young people lists and definitions and having them write sentences containing the new words. We can tell them to memorise the meaning of the word. And, indeed, this is how vocabulary is traditionally taught in schools. But meaning is not something we memorise once and for all. It is something we do.