Stigma (ligature)
In this unrelated function, it is a continuation of the old letter digamma (originally Ϝ, cursive form ), which had served as a numeral since antiquity and was conflated with the σ-τ ligature in the minuscule handwriting of the Middle Ages.[2] Stigma was co-opted as a name specifically for the στ sign, evidently because of the acrophonic value of its initial st- as well as the analogy with the name of sigma.The numeral symbol, originally quite unrelated to the στ ligature, developed from the letter Ϝ, which stood for the sound /w/ in early pre-classical forms of the Greek alphabet.This symbol became obsolete as a letter during the classical era but remained part of the Greek alphabet-based system of numerals, where its value of 6 corresponded to its original place in the alphabet.In modern typefaces, lowercase stigma is similar in appearance to final sigma (ς), but the top loop tends to be larger, and extends farther to the right.