This paper presents a system to find automatically words from a definition or a paraphrase. The system uses a lexical database of French words that is comparable in its size to WordNet and an algorithm that evaluates distances in the semantic graph between hypernyms and hyponyms of the words in the definition. The paper first outlines the structure of the lexical network on which the method is based. It then describes the algorithm. Finally, it concludes with examples of results we have obtained.