[...] let us assume that the output of each word-formation process is submitted within the lexicon itself to the phonological rules of its level. This establishes a basic division among phonological rules into those which are assigned to one or more levels in the lexicon, and those which operate after words have been combined into sentences in the syntax. The former, the rules of "lexical phonology", are intrinsically cyclic because they reapply after each step of word-formation at their morphological level. The latter, the rules of "postlexical phonology", are intrinsecally noncyclic.
- Kiparsky (2004), Pag. 94-95