The letter Esh is a letter in the IPA (a voiceless post-aveolar frictive) that is represented in many languages as Sh,sh or and 's' marked with various diacritcs such as and acute or a wedge (hacek). In some other languages it's appearence is that on a vertically elongated 's' in both upper and lower case, although the capital of Esh is designated as a letter almost indentical to a capital sigma, a form more rarely found amongst languages.