Possible, nonactual words are defined as those words which can be formed by means of established rules of word-formation from actual words (in a finite number of steps, if infinite expressions are disallowed), but which, for some reason, have not seen fit to achieve the status of recognised members of the vocabulary. [...] a nonactual word is a possible word if and only if it is in some rule-governed extension of the lexicon.
- Hoeksma (2004), a pag.187