This study analyzes systematic polysemy in Brazilian Portuguese deverbal nouns as a result of the meaning inherent to deverbal noun formation patterns, which underlies the meaning resulting from the use of those patterns in specific circumstances. Both denotative and grammatical functions are taken into account in the brief description of action, agent and instrumental nouns derived from verbs in Brazilian Portuguese. The data show that, in spite of considerable meaning variation and partial unpredictability, deverbal nouns always maintain a basic meaning necessarily related to the deriving verb, which strongly points to systematic polysemy. In conclusion, the author argues that the situation of systematic polysemy in deverbal nouns derives from the efficiency of the lexicon as a dynamic storage system of symbolic forms for the purposes of language internal and external use. Tradicionalmente a polissemia é definida e entendida como um termo da oposi o homonímia/polissemia, e em rela o à prática lexicográfica. Na lexicografia e lexicologia tradicionais, as palavras s o abordadas como unidades globais, de modo que a dicotomia se refere ao todo e n o a segmentos da estrutura da palavra.