2- Collocations.
In its broadest sense, the term 'collocation' is more or less equivalent to 'recurrent word combination'. In the firthian tradition of British linguistics, however, it is generally used in the stricter sense of 'habitually co-occurring lexical items' or 'mutually selective lexical items' . Both interpretations imply a syntagmatic relationship between linguistic items, but whereas the broad sense focuses on word sequences in texts, the stricter sense goes beyond this notion of textual co-occurrence and emphasizes the relationship between lexical items in language. The former includes idioms, compounds and complex words, and that the letter, cuts across word classes , and presupposes lemmatization. The Firthian notion of collocation is thus a more extensive lexical concept than 'recurrent word combination'. It is well suited for a large-scale corpus study, but such a study is likely to make heavy demands on corpus size, computer capacity and statistical sophistication. Collocations are often described as fixed and recurrent word- combinations …. But both parts of this description are misleading. Typically, collocations are not fixed but variable to a limited and arbitrary degree, As for frequency, it can be shown that individual restricted collocations may recur to only a limited extent within a given text or across several texts devoted to the same topic. It is best to think of a collocation as a familiar (institutionalized), stored (memorized) word-combination with limited and arbitrary variation.
Collocation and semantic prosody
While corpus analysis is concerned with patterns rather than with isolated instances, it is important to deal with the exceptions to certain patterns in some detail. This is because they often given rise to additional meanings that may related to a particular context of use .