Xi (letter) dialects of most of the Greek mainland and Euboea, the sound [ks] was represented by Χ (which in classical Greek is chi, used for ). Because this variant of the Greek alphabet was used in Italy, the Latin alphabet borrowed Χ rather than Ξ as the Latin letter X. While having no Latin derivative, the Xi was adopted into the early Cyrillic alphabet, as the letter ksi (Ѯ, ѯ). The uppercase letter Ξ is used as symbol for: The lowercase letter ξ is used as a symbol for: These characters are used only as mathematical symbols. Stylized Greek text should
Delta (letter) Delta (letter) Delta (uppercase Δ, lowercase δ or 𝛿; "délta", ) is the fourth letter of the Greek alphabet. In the system of Greek numerals it has a value of 4. It was derived from the Phoenician letter dalet 𐤃, Letters that come from delta include Latin D and Cyrillic Д. A river delta (originally, the Nile River delta) is so named because its shape approximates the triangular uppercase letter delta. Despite a popular legend, this use of the word "delta" was not coined by Herodotus. In Ancient Greek, delta represented a voiced dental plosive . In Modern Greek, it