noun one who, or that which, rides.
2. rider ·noun a robber.
3. rider ·noun one who breaks or manages a horse.
4. rider ·noun rock material in a vein of ore, dividing it.
5. rider ·noun the second tier of casks in a vessel's hold.
6. rider ·noun a dutch gold coin having the figure of a man on horseback stamped upon it.
7. rider ·noun a problem of more than usual difficulty added to another on an examination paper.
8. rider ·noun formerly, an agent who went out with samples of goods to obtain orders; a commercial traveler.
9. rider ·noun a small forked weight which straddles the beam of a balance, along which it can be moved in the manner of the weight on a steelyard.
10. rider ·noun an interior rib occasionally fixed in a ship's hold, reaching from the keelson to the beams of the lower deck, to strengthen her frame.
11. rider ·noun 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.