| Definition -
(Aka hole in the pattern)
A word or other form that does not exist in a language but which should exist given the grammatical rules of the language.
For example, a common way of forming an English noun is by adding the suffix -al to a verb (e.g. dismiss → dismissal). There is an English verb describe, but there is no English noun describal, though theoretically such a word should exist. This absence, thus, is an accidental gap.