Morpheme Structure Condition

Morpheme Structure Condition (MSC) is a condition which expresses regularities about the phonological structure of morphemes. It is generally assumed that MSCs may be stated in two ways: either as positive MSCs or as negative ones. A positive MSC of English is that a morpheme may begin with up to three consonants where the first one must be /s/ (e.g. string). Negative ones are that English words may not begin with a velar nasal (*ngam), or end in /h/ (*pah). In recent theories of underspecification, conditions on the phonological shape of morphemes are sometimes expressed by lexical redundancy rules.

Links
Utrecht Lexicon of Linguistics