Abstract. A large class of unsupervised algorithms for Word Sense Disambiguation (WSD) is that of dictionary-based methods. Various algorithms have as the root Lesk's algorithm, which exploits the sense definitions in the dictionary directly. Our approach uses the lexical base WordNet [3] for a new algorithm originated in Lesk's, namely chain algorithm for disambiguation of all words (CHAD). We show how translation from a language into another one and also text entailment verification could be accomplished by this disambiguation.