The Collaborative International Dictionary of English v.0.48:

Alphabet \Al"pha*bet\, n. [L. alphabetum, fr. Gr. ? + ?, the
   first two Greek letters; Heb. [=a]leph and beth: cf. F.
   alphabet.]
   1. The letters of a language arranged in the customary order;
      the series of letters or signs which form the elements of
      written language.
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   2. The simplest rudiments; elements.
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            The very alphabet of our law.         --Macaulay.
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   Deaf and dumb alphabet. See Dactylology.
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The Collaborative International Dictionary of English v.0.48:

Alphabet \Al"pha*bet\, v. t.
   To designate by the letters of the alphabet; to arrange
   alphabetically. [R.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

alphabet
    n 1: a character set that includes letters and is used to write
         a language
    2: the elementary stages of any subject (usually plural); "he
       mastered only the rudiments of geometry" [syn: rudiment,
       first rudiment, first principle, alphabet, ABC,
       ABC's, ABCs]