4. An addition or amendment to a manuscript or other document, which is attached on a separate piece of paper; in legislative practice, an additional clause annexed to a bill while in course of passage; something extra or burdensome that is imposed. After the third reading, a foolish man stood up to propose a rider. Macaulay. This [question] was a rider which Mab found difficult to answer. A. S. Hardy.
5. (Math.)
Defn: A problem of more than usual difficulty added to another on an examination paper.
6. Etym: [D. rijder.]
Defn: A Dutch gold coin having the figure of a man on horseback
stamped upon it.
His moldy money ! half a dozen riders. J. Fletcher.
7. (Mining)
Defn: Rock material in a vein of ore, dividing it.
8. (Shipbuilding)
Defn: An interior rib occasionally fixed in a ship's hold, reaching from the keelson to the beame of the lower deck, to strengthen her frame. Totten.
9. (Naut.)