We describe an approach to the automatic extraction of synonyms that is easy to port across domains and across languages. The approach relies on automatic word alignments in parallel texts and uses distributional methods to compute the semantic similarity of words based on these word alignments. As a result the system outputs ranked lists of candidate synonyms for a given word. We apply the method to French, a language for which an extensive electronic synonym dictionary is available, that serves to evaluate the method. We compare the performance with a system that uses syntactic contexts to acquire synonyms automatically. We show that the alignment-based method outperforms the syntactic method by a large margin. In addition, we show that we can adapt to the domain of colloquial language use by replacing the parallel corpus with one that contains a lot of conversational speech: a corpus of movie subtitles. Furthermore, we apply the method to another language, Dutch, with similar performances.