rider

/ˈraɪdər/ noun [C]

Definition

› LAW, INSURANCE an addition to an official or legal document: You'll need a rider or extra insurance for high-end items such as jewelry, computers, and artwork. The Senate had to accept the rider to the bill that Gorton had crafted with mining industry lobbyists. → See also dispatch rider, free rider

(Definition of rider noun from the Cambridge Business English Dictionary © Cambridge University Press)