Alphabet (noun)

1. A set of letters or symbols in a fixed order used to represent the basic set of speech sounds of a language, especially the set of letters from A to Z.
2. The writing system of a language using such a set of symbols.

Origin:

Late middle english: from old french alphabete, via latin from greek alphabētos, from alpha (the first letter of the greek alphabet) + bētos "second" (the second letter being beta).

Examples:

1. He taught her the alphabet.
2. The Greek alphabet has 24 letters.
3. The Arabic alphabet has 28 letters.
4. The Hebrew alphabet has 22 letters.
5. The Cyrillic alphabet is used in many Slavic languages.