11. A computer implemented method for building a language model for use in a QA system receiving definitional questions, the method comprising: receiving a definitional question and determining a question focus of the definitional question; obtaining information relevant to the question focus; generating a centroid vector based on the question focus and the information relevant to the question focus; generating an ordered centroid based on centroid vector; and building the language model based on the ordered centroid.
11. A computer implemented method for building a language model for use in a QA system receiving definitional questions, the method comprising: receiving a definitional question and determining a question focus of the definitional question; obtaining information relevant to the question focus; generating a centroid vector based on the question focus and the information relevant to the question focus; generating an ordered centroid based on centroid vector; and building the language model based on the ordered centroid. 12. The computer implemented method of claim 11 wherein obtaining information includes searching a source of information using a search engine and a query comprising the question focus and clue words based on a type of the definitional question.