Permanent lexicon

Definition
Permanent lexicon is a list of actual words, where 'actual word' is defined as any word form that some speaker has been observed to use (in ordinary speech). Hence, potential words, which are actually accidental gaps, are not stored in the permanent lexicon.

Example
In English, the permanent lexicon contains actual words such as approve, approval, recite, recital, derive, and describe, but not the potential words derival and describal. Halle (1973) uses the term 'Dictionary' when he refers to the permanent lexicon.

Links
Utrecht Lexicon of Linguistics