13. The system according to claim 8 , wherein the synonym list is for a specific purpose.
8. A system, comprising: a processor; and a memory storing a program, which, when executed on the processor, performs a method for generating a synonym list from a natural language query, the method comprising: preparing a first feature vector from a natural language query and preparing a second feature vector from a result of the natural language query; determining, using a processor, whether a combination of a first feature from the first feature vector and a second feature from the second feature vector is included as a synonym pair in the existing thesaurus; and generating the synonym list by adding the combination to the synonym list when the determination is positive.