We will refer to such new types as neologisms. In the present corpus-based study of types, the notion of "newness" is also used in two slightly different ways. First, when one is going through a corpus from beginning to end, the new types are those that have not been encountered before. [...] Second, the notion "new" bears on the case when we use "P" to predict the rate at which "new" types, new in the sense that they have not been observes in the corpus on the basis of which "P" is calculated, are expected to appear.
- Baayen & Lieber (2004), a pag.73