1. A method of estimating the relevance of a document with respect to a concept ( 12 ) comprises calculating ( 32 ) a relevance function of the concept ( 12 ) with respect to said document on the basis of a known predetermined semantic neighborhood of the concept ( 12 ), and is characterized in that, if the document is considered to be relevant with respect to the concept: there is calculated ( 42 ) an ambiguity function of said concept ( 12 ) in said document, which ambiguity function is different from the relevance function, said calculation being an estimation related to different meanings of the concept in document, and a result of the calculation of the ambiguity function is associated ( 44 ) with the document considered to be relevant.