An aspect of the present disclosure relate to translating natural language queries into native database queries. For example, a database application receives a natural language query from a user, divides the query into clauses, determines keywords from the clauses, and maps keywords in the query to native query that can query a database. In the case that the natural language query includes keywords that are not mapped, the application resolves an ambiguity by communicating with a user device. In the case that a keyword cannot be mapped, the application can map the keyword to a custom index that includes synonyms derived using pair-wise generalization or other techniques. Once all keywords are mapped, the database application generates a native database query and obtains results from a database.