Topic summary
Delta (letter)
Delta ( ; uppercase Δ, lowercase δ; Greek: δέλτα, délta, ) is the fourth letter of the Greek alphabet. In the system of Greek numerals, it has a value of four. It was derived from the Phoenician letterdalet 𐤃. Letters that come from delta include the LatinD and the CyrillicД.
A river delta (originally, the delta of the Nile River) is named so because its shape approximates the triangular uppercase letter delta. Contrary to a popular legend, this use of the word delta was not coined by Herodotus.