Source : Free On-Line Dictionary of Computing

weighted search
     
         A search based on frequencies of the
        {search terms} in the documents being searched.  Weighted
        search is often used by {search engines}.  It produces a
        numerical score for each possible document.  A document's
        score depends on the frequency of each {search term} in that
        document compared with the overall frequency of that term in
        the entire corpus of documents.  A common approach is called
        tf.idf which stands for term frequency * inverse document
        frequency.  Term frequency means "the more often a term occurs
        in a document, the more important it is in describing that
        document."
        {http://ciir.cs.umass.edu/cmpsci646/ir4/tsld034.htm} Inverse
        document frequency means the more documents a term appears in,
        the less important the term is.
     
        A simple weighted search is just a list of search terms,
        for example: car automobile
     
        Weighted search is often contrasted with {boolean search}.
        It is possible to have a search that syntactically is a
        boolean search but which also does a weighted search.
     
        See also {query expansion}.
     
        For a detailed technical discussion see Chapter 5,
        "Search Strategies", in the reference below.
     
        [{"Information Retrieval", C. J. van Rijsbergen,
        (http://www.dcs.gla.ac.uk/Keith/Chapter.5/Ch.5.html)}].
     
        (1999-08-28)