Noun
The 18th Ancient Greek letter in early versions of the Greek alphabet, Ϙ (lowercase ϙ).
The Greek numeral Ϟ (lowercase ϟ), descended from the ancient letter and having the numerical value of 90.
The archaic Cyrillic numeral Ҁ (lowercase ҁ), descended from the ancient Greek letter and having the numerical value of 90.
Source: en.wiktionary.orgGlyph confusion Example of a nineteenth-century font using S-shaped capital Stigma (first row) and G-shaped capital Koppa (second row). Source: Internet