Multilingual dictionaries are very useful in machine translations and natural language processing. However, a multilingual dictionary including all natural languages still does not exist. In this paper we propose a trustworthy method to automatically create multilingual dictionary represented by N-lingual synonymous word sets (N-tuples, hereafter). Based on the work of 3-lingual synonymous word sets, our method has extended 3-lingual to n-lingual synonymous word sets from multiple bilingual dictionaries. By matching and combining the triples instead of the binary relations in the bilingual dictionaries, the complexity of the problem is significantly reduced. Using this method, we created 4-lingual synonymous word sets among Chinese, Japanese, English and German. The evaluations indicate that our combining algorithm has effectively solved the error accumulation problem and achieved a very promising quality. In the example application, the 4-tuples are used to refine the translation quality of a multi-hop machine translator created on the Language Grid. It shows that utilizing the handy online services and uniform platform in research work is a good methodology.