In order to increase relevant retrieved results and users satisfaction, information retrieval systems are seeking a way to change keyword-based search to concept-based search. These systems use the tools that can convert terms to concepts. Over the years, this provided the basis for production of tools such as classification schema, vocabularies, subject headings and thesauri. Recently, ontologies are used in complementing this process.
The main problem of this research is how the great information retrieval systems of the world claiming to use ontologies and thesauri use the semantic features of these tools in their information retrieval process? In this paper 7 information retrieval systems which use these tools, were selected. Using literature review, the semantic features were presented in the form of research checklist. These features include 5 general categories of concept search, synonyms search, suggestion for search, use of ontologies and display. The researcher examined these features with structured observation in the form of checklist. Though these systems use these tools for searching and retrieving, they don`t show the expected features. In studied factors, ERIC Database and the National Library of Australia achieved maximum scores of 32 and 24 respectively, while the National Archive of Australia and the British Museum had minimum scores of 12 and 13 respectively.