1. A system, comprising: one or more computer processors; and a memory containing a program, which, when executed by the one or more computer processors, performs an operation for query processing based on normalized search terms, the operation comprising: responsive to receiving a query, generating a normalized search term for a concept in the query based on a first language model, of a plurality of language models each having a predefined association with a respective concept; modifying the query to include the normalized search term; executing the modified query against an indexed corpus of evidence including a first item of evidence; and upon determining that the first item of evidence includes the normalized search term, returning the first item of evidence as responsive to the query.