Nolo's Plain-English Law Dictionary

Rider

1) An attachment to a document that adds to or amends it. Typical is an added provision to an insurance policy, such as additional coverage for a valuable item or temporary insurance to cover a public event. 2) An amendment tacked on to a legislative bill that has little or no connection to the main purpose of the legislation, as a way to get the amendment passed.
NOLO4:DRU1.6.8.11.20160427.37128