From WordNet (r) 3.0 (2006) [wn]:
rider
n 1: a traveler who actively rides an animal (as a horse or
camel)
2: a clause that is appended to a legislative bill
3: a traveler who actively rides a vehicle (as a bicycle or
motorcycle)
4: a traveler riding in a vehicle (a boat or bus or car or plane
or train etc) who is not operating it [syn: passenger,
rider]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Rider \Rid"er\ (r[imac]d"[~e]r), n.
1. One who, or that which, rides.
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2. Formerly, an agent who went out with samples of goods to
obtain orders; a commercial traveler. [Eng.]
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3. One who breaks or manages a horse. --Shak.
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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.
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After the third reading, a foolish man stood up to
propose a rider. --Macaulay.
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This [question] was a rider which Mab found
difficult to answer. --A. S. Hardy.
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5. (Math.) A problem of more than usual difficulty added to
another on an examination paper.
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6. [D. rijder.] A Dutch gold coin having the figure of a man
on horseback stamped upon it.
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His moldy money ! half a dozen riders. --J.
Fletcher.
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7. (Mining) Rock material in a vein of ore, dividing it.
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8. (Shipbuilding) 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. --Totten.
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9. (Naut.) The second tier of casks in a vessel's hold.
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10. 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.
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11. A robber. [Obs. or Prov. Eng.] --Drummond.
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Rider's bone (Med.), a bony deposit in the muscles of the
upper and inner part of the thigh, due to the pressure and
irritation caused by the saddle in riding.
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