An insurance policy form that either changes or adds to the provisions included in one or more other forms used to construct the policy, such as the declarations page or the coverage form. Insurance policy endorsements may serve any number of functions, including broadening the scope of coverage, limiting or restricting the scope of coverage, clarifying the application of coverage to some unique loss exposure, adding other parties as insureds, or adding locations to the policy. They often effect these changes by modifying the existing insuring agreement, policy definitions, exclusions, or conditions in the coverage form or adding additional information, such as insured locations, to the declarations page.
Definition provided by the International Risk Management Institute (IRMI) Glossary of Insurance.