Stigma (letter) sigma form ς never occurs inside a word and is never used as a numeral either. Uppercase forms of stigma as a numeral (Ϛ) are rare in practice; when they occur, they can often be confused with uppercase forms of another numeral symbol, koppa (Ϟϟ), which stands for 90. Stigma is encoded in Unicode as "Greek letter stigma" U+03DA (Ϛ) and "Greek small letter stigma" U+03DB (ϛ). Stigma (letter) Stigma (ϛ) is a ligature of the Greek letters sigma (Σ) and tau (Τ), which was used in writing Greek between the Middle Ages and the 19th century. It is also
Delta (letter) represents a voiced dental fricative , like the "th" in "that" or "this". It is romanized as "d" or "dh". The uppercase letter Δ can be used to denote: The lowercase letter δ (or 𝛿) can be used to denote: 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. 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