Greek alphabet glottal ("heth") was borrowed in two different functions by different dialects of Greek: as a letter for /h/ (Η, heta) by those dialects that had such a sound, and as an additional vowel letter for the long (Η, eta) by those dialects that lacked the consonant. Eventually, a seventh vowel letter for the long (Ω, omega) was introduced. Greek also introduced three new consonant letters for its aspirated plosive sounds and consonant clusters: Φ ("phi") for , Χ ("chi") for and Ψ ("psi") for . In western Greek variants, Χ was instead used for and Ψ for . The origin
Letter (alphabet) letters have prescribed orders, although this too may vary by language. In Spanish, for instance, "ñ" is a separate letter, sorted after "n". In English, "n" and "ñ" are classified alike. As symbols that indicate segmental speech, letters are associated with phonetics. In a purely phonemic alphabet, a single phoneme is denoted by a single letter, although in history and in practice letters often indicate more than one phoneme. There are more sounds, or phonemes, in English–about 44–than there are letters of the alphabet. A letter may therefore be associated with more than one phoneme, with the phoneme determined by