Sho (uppercase Ϸ, lowercase ϸ) was a letter added to the Greek alphabet in order to write the Bactrian language. It probably represented a sound similar to English "sh" (IPA: [ʃ]).
It is similar in appearance to Latin thorn (þ).
The content of this page is retrieved from http://en.wikipedia.org/wiki/Sho_%28letter%29 under GFDL