This article explores the polysemy of four negative non-verbal prefixes in Persian language (zedd 'against, opposite of', bi 'without', nā 'not' and qejr 'not, non-') based on Principled Polysemy framework (Tyler and Evans 2001, 2003). First, the primary sense of each prefix is determined and then it is explained how non-primary senses are derived from the primary one, hence demonstrating the semantic network of each prefix as a radial category. In this research, using AntConc software (Anthony, 2014), first all the occurrences of the four prefixes were extracted from the Hamshahri Corpus Version 2 (AleAhmad, Amiri, Darrudi, Rahgozar & Oroumchian, 2009) and then in order to analyze research data, some of them were randomly selected. The findings of the study indicate that only in three of the four prefixes under study, polysemy is observed, and that the frequency of use, ease of derivation and predominance in the semantic network are the best criteria for determining the primary sense. The conceptual phenomenon involved in the polysemy of these prefixes is metonymy. Data analysis shows that metonymical shift occurs at two levels: at the level of morpheme/prefix sense and at the level of word-formation, and that the former leads to more straightforward relations within the semantic network. This is due to the fact that the latter requires a more complex line of imagination which automatically translates into a corresponding complexity of relations in the semantic network and significant reduction in the type frequency of non-primary senses as a whole.
