Sha (Cyrillic)

Sha, She or Shu, alternatively transliterated Ša (Ш ш; italics: Ш ш ) is a letter of the Glagolitic and Cyrillic scripts. It commonly represents the voiceless postalveolar fricative, like the pronunciation of sh in "ship". More precisely, the sound in Russian denoted by ш is commonly transcribed as a palatoalveolar fricative but is actually a voiceless retroflex fricative. It is used in every variation of the Cyrillic alphabet for Slavic and non-Slavic languages.

In English, Sha is romanized as sh or as š, the latter being the equivalent letter in the Latin alphabets of Czech, Slovak, Slovene, Serbo-Croatian, Macedonian, Latvian and Lithuanian.

History
Sha has its earliest origins in Phoenician Shin and is possibly linked closely to Shin's Greek equivalent: Sigma (Σ, σ, ς). (The similar form of the modern Hebrew Shin (ש), which is probably where the Cyrillic letter was actually derived from, derives from the same Proto-Canaanite source). Sha already possessed its current form in Saints Cyril and Methodius's Glagolitic alphabet. Most Cyrillic letter-forms were derived from the Greek, but as there was no Greek sign for the Sha sound (modern Greek uses simply "Σ/σ/ς" to spell the sh-sound in foreign words and names), Glagolitic Sha (Ⱎ) was adopted unchanged. There is also a possibility that Sha was taken from the Coptic alphabet, which is the same as the Greek alphabet but with a few letters added at the end, including one called "shai" (Ϣϣ) which somewhat resembles both sha and shcha (Щ, щ) in appearance.

Usage
Sha is used in the alphabets of all Slavic languages using a Cyrillic alphabet, and of most non-Slavic languages which use a Cyrillic alphabet. The position in the alphabet and the sound represented by the letter vary from language to language.

Use in mathematics
The Cyrillic letter Ш is internationally used in mathematics for several concepts:

In algebraic geometry, the Tate–Shafarevich group of an Abelian variety A over a field K is denoted Ш(A/K), a notation first suggested by J. W. S. Cassels. (Previously it had been denoted TS.) Presumably the choice comes from the first letter of Шафаре́вич = Shafarevich.

In a different mathematical context, some authors allude to the shape of the letter Sha when they use the term Shah function for what is otherwise called a Dirac comb.

The shuffle product is often denoted by ш.

Related letters

 * ش : Arabic letter ش
 * श: श|Devanagari letter श
 * ष: ष|Devanagari letter ष
 * श़: Devanagari letter श़
 * Ⱎ : Glagolitic letter Sha/ša
 * Ⱋ : Glagolitic letter Shta/šta or Shcha/šča
 * Щ щ : Cyrillic letter Shcha
 * ⧢ : Shuffle product
 * Ʃ ʃ : Latin letter Esh
 * Š š : Š|Latin letter S with caron
 * Ŝ ŝ : Ŝ|Latin letter S with circumflex
 * Ş ş : Ş|Latin letter S with cedilla
 * Ș ș : Latin letter S with comma below