Delta (uppercase Δ, lowercase 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 delta of the Nile River) is so named 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.

Pronunciation

In Ancient Greek, delta represented a voiced dental plosive. In Modern Greek, it represents a voiced dental fricative, like the "th" in "that" or "this" (while in foreign words is instead commonly transcribed as ντ). Delta is romanized as d or dh.

Uppercase

The uppercase letter Δ is used to denote:

Lowercase

The lowercase letter δ (or 𝛿) can be used to denote:

Unicode

These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style: