ABSTRACT
At an earlier stage in the development of generative grammar, when morphology was largely ignored, the lexicon was simply viewed as an unstructured list of lexical items (Chomsky 1965). However, the Lexicalist Hypothesis (Chomsky 1970) brought about a renewed interest in word formation, and it is now clear that the lexicon has a rich internal structure. Much of the recent work on morphology has focused on the principles governing the internal structure of words and the relationship of this to syntax (e.g., Aronoff 1976; Lieber 1980; Williams 1981b). A related and equally important issue that has not received as much attention is the question of how lexical items, both simple and complex, are actually listed in the lexicon. Are lexical items simply listed without regard to shared features, or are there organizing principles that group some items together? One observation, made by Aronoff (1976), indicates that lexical items are organized in the lexicon according to their meaning. Aronoff notes that when a morphologically complex word potentially shares the same semantic space as a simple one (e.g., *gloriosity, glory), the former is blocked from occurring in the language. Clark and Clark (1979) have observed the same phenomenon (they name it preemption) with a wide range of denominal verbs. The idea of blocking presupposes a lexicon that is structured into groups of semantic slots. The slots grouped together share a signifi cant semantic feature, and all lexical items that receive an entry must fi nd an appropriate slot to enter. When a morphological derivative is produced from a base belonging to group X, the derivative must fi nd a slot in X to enter in order for it to receive an entry; if the appropriate slot is already fi lled, the derivative is blocked from occurring in the language.
