Chi (letter) in the context of "Epichoric alphabets"

Transliteration is a type of conversion of a text from one script to another that involves swapping letters (thus trans- + liter-) in predictable ways, such as Greek ⟨α⟩ → ⟨a⟩ and ⟨χ⟩ → the digraph ⟨ch⟩, Cyrillic ⟨д⟩ → ⟨d⟩, Armenian ⟨ն⟩ → ⟨n⟩ or Latin ⟨æ⟩ → ⟨ae⟩.

For instance, for the Greek term ⟨Ελληνική Δημοκρατία⟩, which is usually translated as 'Hellenic Republic', the usual transliteration into the Latin script (romanization) is ⟨Hellēnikḗ Dēmokratía⟩; and the Russian term ⟨Российская Республика⟩, which is usually translated as 'Russian Republic', can be transliterated either as ⟨Rossiyskaya Respublika⟩ or alternatively as ⟨Rossijskaja Respublika⟩.

Many local variants of the Greek alphabet were employed in ancient Greece during the archaic and early classical periods, until around 400 BC, when they were replaced by the classical 24-letter alphabet that is the standard today. All forms of the Greek alphabet were originally based on the shared inventory of the 22 symbols of the Phoenician alphabet, with the exception of the letter Samekh, whose Greek counterpart Xi (Ξ) was used only in a subgroup of Greek alphabets, and with the common addition of Upsilon (Υ) for the vowel /u, ū/. The local, so-called epichoric, alphabets differed in many ways: in the use of the consonant symbols Χ, Φ and Ψ; in the use of the innovative long vowel letters (Ω and Η), in the absence or presence of Η in its original consonant function (/h/); in the use or non-use of certain archaic letters (Ϝ = /w/, Ϙ = /k/, Ϻ = /s/); and in many details of the individual shapes of each letter. The system now familiar as the standard 24-letter Greek alphabet was originally the regional variant of the Ionian cities in Anatolia. It was officially adopted in Athens in 403 BC and in most of the rest of the Greek world by the middle of the 4th century BC.

In chemistry, the mole fraction or molar fraction, also called mole proportion or molar proportion, is a quantity defined as the ratio between the amount of a constituent substance, n_i (expressed in unit of moles, symbol mol), and the total amount of all constituents in a mixture, n_tot (also expressed in moles):

It is denoted x_i (lowercase Roman letter x), sometimes χ_i (lowercase Greek letter chi). (For mixtures of gases, the letter y is recommended.)

Xi (/zaɪ/ ZY or /(k)saɪ/ (K)SY; uppercase Ξ, lowercase ξ; Greek: ξι) is the fourteenth letter of the Greek alphabet, representing the voiceless consonant cluster [ks]. Its name is pronounced [ksi] https://upload.wikimedia.org/wikipedia/commons/3/3c/De-Xi.ogg in both Ancient Greek and Modern Greek. In the system of Greek numerals, it has a value of 60. Xi was derived from the Phoenician letter samekh .

Xi is distinct from the letter chi, which gave its form to the Latin letter X.

In rhetoric, chiasmus (/kaɪˈæzməs/ ky-AZ-məs) or, less commonly, chiasm (Latin term from Greek χίασμα chiásma, "crossing", from the Greek χιάζω, chiázō, "to shape like the letter Χ"), is a "reversal of grammatical structures in successive phrases or clauses – but no repetition of words".

A similar device, antimetabole, also involves a reversal of grammatical structures in successive phrases or clauses in an A-B-B-A configuration, but unlike chiasmus, presents a repetition of words.