1. A letter of an alphabet.
2. All of the letters and letter combinations that represent a phoneme, as f, ph, and gh for the phoneme /f/.
1935–40; graph- (combining form from Greek graphē, "writing") + -eme (from French suffix -ème, as extracted from phonème, originally from Greek phōnēma, "sound")
Alphabet: most graphemes in this type of writing system convey a single sound, not an entire syllable. Alphabetic graphemes are called letters. --Linguistics 201: A Study Guide to the History of Writing