The traditional definition of inflective classes in Serbo-Croatian lexicography does not link entries with a close structural derivation relationship between them. Such relationship is usually expressed in dictionaries by a stereotyped definition based on the meaning of the basic entry. Several types of derivation from nominal bases of this kind are discussed in this paper: grammatical gender change, formation of diminutives and augmentatives, and derivation of adjectives from nouns. It is shown that all form the new noun from the initial one according to the same model and in a similar way as inflective classes are represented. The extension of the traditional nominal class can thus be seen as a tuple of the elementary classes that describe the derivatives of the basic entry.