A canonicalizer can be used with or implemented within a natural language understanding (NLU) component of a speech processing system to enable the system to properly identify an entity to which a user refers in a spoken utterance. The canonicalizer may determine a first canonical value using a gazetteer associated with a determined intent of the spoken utterance. The canonicalizer may determine a second canonical value using a look-up table of canonical values. The canonicalizer may then output either the first canonical value or the second canonical value for further NLU processing, such as entity resolution.