Shin (letter) languages, as follows: In the Arabic alphabet, ' is at the original (21st) position in Abjadi order. A letter variant ' takes the place of Samekh at 15th position. "" represents , and is the 13th letter of the modern alphabet order and is written thus: The Arabic letter "šīn" was an acronym for "something" ( "šayʾ(un)" ) meaning the unknown in algebraic equations. In the transcription into Spanish, the Greek letter "chi" (χ) was used which was later transcribed into Latin "x". According to some sources, this is the origin of "x" used for the unknown in the equations.
Greek alphabet late ninth century BC or early eighth century BC, the Greek alphabet emerged. The period between the use of the two writing systems, during which no Greek texts are attested, is known as the Greek Dark Ages. The Greeks adopted the alphabet from the earlier Phoenician alphabet, one of the closely related scripts used for the West Semitic languages. However, the Phoenician alphabet is limited to consonants. When it was adopted for writing Greek, certain consonants were adapted to express vowels. The use of both vowels and consonants makes Greek the first alphabet in the narrow sense, as distinguished from