The Synonyms Dictionary has been introduced in dLibra library in order to improve mechanism of searching library resources. User entering a phrase which has to be a key for searching may decide to extend the query by information included in dictionary. It gives them a better chance to find publications they looked for and on the other hand doesn't require for them to know the specific format of data used in attributes' values.

In example, let user input in a filed "author" value "Shakespeare" to search for library resources. If this query will be processed without synonymous extension only publications containing values with a character subset "Shakespeare" for an attribute "author" in bibliographic description will be found. However, if there is a group containing both values "Shakespeare" and "Szekspir" (polish translation of the name) for attribute "author", then user deciding to extend the query with a dictionary information will get as a result list of all publications that have "Shakespeare" or "Szekspir" set as an "author" value. This means that they don't have to know which format of this writer's name was used by librarians to describe his publications. The other examples of synonymous connection between attribute values may be: putting "picture" and "photo" in the same group for "format" attribute, or putting "polish", "polski" (polish translation of "polish" word), "pol" and "pl" in the same group for "language" attribute.