Old Uyghur letter samekh

It marks an s consonant in an Old Uyghur word.

The letter contributes a sound; the whole word supplies its meaning.

Old Uyghur grew from cursive Sogdian, a Central Asian script, in the 8th–9th centuries; its known letter repertoire is based on 9th-century documents. Samekh adapts Sogdian Semkath, turned 90° counterclockwise. The script first wrote medieval Turkic languages, then Chinese, Mongolian, Tibetan and Arabic. It flourished during the 8th–17th centuries in books, official records, religious texts and literature, and became the ancestor of Mongolian script.

Why do samekh and shin share a form?

Later Old Uyghur writing merged the two s-letters.

By the 11th century, both could use the shin form 𐽿: samekh without a mark, shin with two dots below (𐽿𐾅). A bare form in a manuscript can therefore be ambiguous; surrounding words may identify it.

Old Uyghur letters join, so a letter’s outline changes when it stands alone or at the beginning, middle or end of a word. Formal book writing uses a square style; quicker handwriting uses a cursive style. Fonts and manuscripts can show these styles differently.