The Collaborative International Dictionary of English v.0.48:

Score \Score\ (sk[=o]r), n. [AS. scor twenty, fr. sceran,
   scieran, to shear, cut, divide; or rather the kindred Icel.
   skor incision, twenty, akin to Dan. skure a notch, Sw.
   sk[*a]ra. See Shear.]
   1. A notch or incision; especially, one that is made as a
      tally mark; hence, a mark, or line, made for the purpose
      of account.
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            Whereas, before, our forefathers had no other books
            but the score and the tally, thou hast caused
            printing to be used.                  --Shak.
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   2. An account or reckoning; account of dues; bill; hence,
      indebtedness.
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            He parted well, and paid his score.   --Shak.
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   3. Account; reason; motive; sake; behalf.
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            But left the trade, as many more
            Have lately done on the same score.   --Hudibras.
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            You act your kindness in Cydaria's score. --Dryden.
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   4. The number twenty, as being marked off by a special score
      or tally; hence, in pl., a large number.
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            Amongst three or four score hogsheads. --Shak.
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            At length the queen took upon herself to grant
            patents of monopoly by scores.        --Macaulay.
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   5. A distance of twenty yards; -- a term used in ancient
      archery and gunnery. --Halliwell.
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   6. A weight of twenty pounds. [Prov. Eng.]
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   7. The number of points gained by the contestants, or either
      of them, in any game, as in cards or cricket.
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   8. A line drawn; a groove or furrow.
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   9. (Mus.) The original and entire draught, or its transcript,
      of a composition, with the parts for all the different
      instruments or voices written on staves one above another,
      so that they can be read at a glance; -- so called from
      the bar, which, in its early use, was drawn through all
      the parts. --Moore (Encyc. of Music).
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   10. the grade received on an examination, such as those given
       in school or as a qualifying examination for a job or
       admission to school; -- it may be expressed as a
       percentage of answers which are correct, or as a number
       or letter; as, a score of 98 in a civil service exam.
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   In score (Mus.), having all the parts arranged and placed
      in juxtaposition. --Smart.

   To quit scores, to settle or balance accounts; to render an
      equivalent; to make compensation.
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            Does not the earth quit scores with all the elements
            in the noble fruits that issue from it? --South.
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