alphabet

1. The set of letters used when writing in a language.

   In the first year of school, pupils are taught to recite the alphabet.

2. A writing system in which letters represent phonemes. (Contrast e.g. logography, a writing system in which each character represents a word, and syllabary, in which each character represents a syllable.)
3. A typically finite set of distinguishable symbols.

   Let L be a regular language over the alphabet \Sigma.

4. An individual letter of an alphabet; an alphabetic character.
5. The simplest rudiments; elements.

verb

To designate by the letters of the alphabet; to arrange alphabetically.