This work investigates the meanings of the prefix re- as a morphological element used in verb formation in Brazilian Portuguese. It concentrates on the question of lexical productivity and its relation to the polysemic and/ or multifunctional aspect of word formation. Initially, we analyse several approaches to word formation by prefixation in Portuguese, examining the precepts of traditional grammar, the point of view of the structuralists and the generative view on the phenomenon. Then we present and discuss different descriptive proposals for the prefix re- in Portuguese. Next, we discuss the complex notion of productivity in lexical theory and introduce the question of polysemy in lexical constructions and its relevance in determining specific processes in word formation. Having in mind the theoretical issues brought into our previous discussion, we then analyse the relation between productivity and polysemy in the Word Formation Rule of re- addition in Portuguese verb formation. The analysis is based on corpora consisting both of contemporary written newspaper language and of standard spoken language (NURC data) of about the same length. Our results reveal the polysemic nature of the prefix re- in contemporary Portuguese and point to the precariousness of current descriptions which focus on the notion of repetition as being the sole productive semantic contribution of the prefix re- in verb formation. Furthermore, the research shows that it is possible to predict the meaning(s) of a re- + V formation on the basis of the semantic properties of the basic verb. This strongly supports the hypothesis that the multiplicity of meanings of the prefix re- does not constitute a case of random or incidental polysemy, but rather accounts for a phenomenon generated by a convergence of meanings which leads towards a functional direction in word formation by prefixation.