The chapter investigates the workings of conceptual metonymy in the creation of polysemy. The author's aim is to show that metonymy is fundamental to the functioning of the lexicon as a dynamic storage system of symbolic forms. The author demonstrates that agent nouns in Portuguese are interpreted on the basis of metonymic models. Agent nouns in this language include formations in -dor (e.g. governador 'governor'), -nte (e.g. estudante 'student'), -eiro (porteiro 'doorman'), and -ista (e.g. neurologista 'neurologist'). These suffixes are polysemous, i.e., they form families of metonymically related meanings. The term 'agent noun' of course does not cover the full range of meanings of these nouns, but it is motivated to the extent that e.g. the use of -dor for instrument nouns (as in e.g. refrigerador 'refrigerator') is metonymically derivable from the source meaning agent (see Panther & Thornburg 2002 on -er nouns in English). The derived instrument sense is conceptually prominent, but the source meaning agent is still a (backgrounded) part of the foregrounded instrumental reading; thus the distributional properties of such metonymically derived -dor nouns would be expected to follow from their metonymically derived meaning. (Margarida Basilio)