Stratificational Linguistics is a view of linguistics advocated by Sydney Lamb

Sydney Lamb

Sydney MacDonald Lamb is an American linguist and professor at Rice University, whose stratificational grammar is a significant alternative theory to Chomsky's transformational grammar....

. His theories advocate that language usage and production is stratificational in nature.

Specifically, that there are separate 'strata' or levels in the brain used for language. Each level provides actualization or 'realization' for the next higher level, and the elements on its level are similar to each other.
Several strata are involved in the production of a sound from an initial idea.

Some strata include:

• Phoneme
  Phoneme
  In a language or dialect, a phoneme is the smallest segmental unit of sound employed to form meaningful contrasts between utterances....
  
   as the unit on the Phonemic strata.
• Lexeme
  Lexeme
  A lexeme is an abstract unit of morphological analysis in linguistics, that roughly corresponds to a set of forms taken by a single word. For example, in the English language, run, runs, ran and running are forms of the same lexeme, conventionally written as RUN...
  
   as a unit on the Lexical strata.
• Morpheme
  Morpheme
  In linguistics, a morpheme is the smallest semantically meaningful unit in a language. The field of study dedicated to morphemes is called morphology. A morpheme is not identical to a word, and the principal difference between the two is that a morpheme may or may not stand alone, whereas a word,...
  
   as the unit on the Morphemic strata
• Sememe
  Sememe
  A sememe is a semantic language unit of meaning, correlative to a morpheme.A sememe is a proposed unit of transmitted or intended meaning; it is atomic or indivisible. A sememe can be the meaning expressed by a morpheme, such as the English pluralizing morpheme -s, which carries the sememic...
  
   as the unit on the Semantic strata.