Sigma (upper case Σ, lower case σ, lower case in word-final position ς; Greek σίγμα) is the eighteenth letter of the Greek alphabet, and carries the 'S' sound. In the system of Greek numerals it has a value of 200. When used at the end of a word, and the word is not all upper case, the final form (ς) is used, e.g. Ὀδυσσεύς (Odysseus) – note the two sigmas in the center of the name, and the word-final sigma at the end.

The shape and alphabetic position of Sigma is derived from Phoenician shin 𐤔 .

The name of sigma, according to one theory, may continue that of Phoenician Samekh. According to a different theory, its original name may have been "San" (the name today associated with another, obsolete letter), while "Sigma" was a Greek innovation that simply meant "hissing", based on a nominalization of a verb σίζω (sízō, from earlier *sig-jō, meaning 'I hiss').

The uppercase form of sigma was re-borrowed into the Latin alphabet to serve as the uppercase of modern esh (lowercase: ʃ).

In handwritten Greek during the Hellenistic period (4th and 3rd centuries BC), the epigraphic form of Σ was simplified into a C-like shape. It is also found on coins from the fourth century BC onwards. This became the universal standard form of Sigma during late antiquity and the Middle Ages. It is today known as lunate sigma (upper case Ϲ, lower case ϲ), because of its crescent-like shape.

Chi may refer to:

CHI may stand for:

Juaquin Malphurs (born May 31, 1986), better known by his stage name Waka Flocka Flame, is an American rapper signed to 1017 Brick Squad and Warner Bros. He is a Southern hip hop artist best known for his singles "O Let's Do It", "Hard in da Paint" & "No Hands", along with his debut album, Flockaveli. Waka Flocka Flame has announced that his second album, Triple F Life: Friends, Fans and Family, will be released during the spring of 2012.

Juaquin Malphurs was born in South Jamaica, Queens, New York in 1986. His family eventually settled in Riverdale, Georgia. He is the son of Debra Antney, Gucci Mane's former manager and CEO of So Icey/Mizay Entertainment. The name "Waka" was given to him by his cousin, after the Muppets character Fozzie Bear's catch phrase, "Waka Waka". The name "Flocka Flame" was given to him by rapper Gucci Mane. Waka Flocka posed for a nude but unrevealing picture for the company PETA to boycott killing animals. The picture says "Ink not Mink". The picture design is similar to Waka Flocka Flame's album Flockaveli. Waka Flocka Flame said that he has known Gucci Mane since he was 19