We propose a corpus-based study on nouns which have a dynamic lexical aspect (NDYN). They combine with light verbs expressing action such as accomplir ‘carry out’, effectuer ‘make’ and procéder à ‘proceed in’, where they are action nouns, and/or they combine with event predicates such as avoir lieu ‘take place’ and se produire ‘occur’, where they are event nouns. Many NDYN can denote an action or an event according to the context. Nevertheless, the existence of nouns denoting only actions or only events leads us to assume two nominal types which are distinguished by their degree of semantic autonomy, their agentivity and their causality.