1. A method for constructing a glossary operable to mask word noise features in at least two documents, the method comprising: a) providing the at least two documents that are similar in accordance with a criterion, the word noise features being nominally identical features that appear differently in the documents; b) providing a discrepancy list for the at least two documents that includes the word noise features; and c) constructing a glossary for masking the word noise features utilizing at least the discrepancy list, wherein said constructing includes: mapping the word noise features utilizing said discrepancy list to common mapped features and automatically adding said mapped features to the glossary; and said mapping includes: (i) identifying, utilizing said discrepancy list, a pair of word noise features appearing in respective two documents; and (ii) mapping said pair of word noise features to a common mapped feature including applying Feature Mapping Function (FMF) in respect of said pair of word noise features, said FMF gets a word noise feature in a document of said two documents and returns said mapped feature and in the case that said FMF is not in the glossary, adding said FMF to the glossary.