This study revisits the query–document terms mismatch problem and discusses identified perceptions on language, meaning and knowledge organisation, mainly of Ludwig Wittgenstein, in view of query expansion. We conducted literature review on query expansion techniques, knowledge organisation in general, as well as systems and Wittgenstein’s theories on respective issues. The analysis commences from the discussion of the query–document terms mismatch problem and proceeds to the allocation of theories on the aforementioned issues. Additionally, we mention query expansion techniques in view of the definition of what constitutes the context of the query. We identify a theoretical background concerning the context which current query expansion techniques try to define and further exploit to the benefit of the searcher.