We propose an original automatic alignment of definitions taken from different dictionaries that could be associated to the same concept although they may have different labels. The alignment between a specialized terminology used by the librarians to index concepts and a general vocabulary employed by a neophyte user in order to retrieve documents on Internet, will certainly improve the performances of the information retrieval process. The selected framework is a medical one. We propose a terminology alignment by an SVM classifier trained on a compact, but relevant representation of such definition pair by several similarity measures and the length of definitions. Three syntactic levels are investigated: Nouns, Nouns-Adjectives, and Nouns-Adjectives-Verbs. Our aim is to show how the combination of similarity measures offers a better semantic access to the document content than only one measure and it improves the performances of the automatic alignment. The results obtained on the te...