From Wikipedia, the free encyclopedia

Look up Ω, ω in Wiktionary, the free dictionary.

Greek alphabet
Αα Alpha	Νν Nu
Ββ Beta	Ξξ Xi
Γγ Gamma	Οο Omicron
Δδ Delta	Ππ Pi
Εε Epsilon	Ρρ Rho
Ζζ Zeta	Σσ Sigma
Ηη Eta	Ττ Tau
Θθ Theta	Υυ Upsilon
Ιι Iota	Φφ Phi
Κκ Kappa	Χχ Chi
Λλ Lambda	Ψψ Psi
Μμ Mu	Ωω Omega
Obsolete letters
Ϝϝ Digamma	Ϙϙ Qoppa
Ϛϛ Stigma	Ϡϡ Sampi
Ϻϻ San	Ϸϸ Sho
Greek diacritics

Note: This article contains special characters.

Omega (uppercase Ω, lowercase ω) is the 24th and last letter of the Greek alphabet. In the Greek numeric system, it has a value of 800. The word literally means "great O" (ō mega, mega meaning 'great'), as opposed to Omicron, which means "little O" (o mikron, micron meaning "little").^[1] This name is Byzantine; in Classical Greek, the letter was called ō (ὦ), whereas the Omicron was called ou (οὖ).^[2] The form of the lowercase letter derives from a double omicron, which came to be written open at the top.

Phonetically, the Ancient Greek Ω is a long open-mid o [ɔː], similar to the vowel of English raw in certain dialects such as RP where this word is pronounced [ɹɔː]. It should not be confused with the sound of English so-called "long o" as in ocean, which is either diphthongal [oʊ] or [əʊ] or a close-mid kind of "o" [o], in either case distinctly different from the "long o" sound of Greek omega and closer to the Classical Greek sound represented by ου before this came to be pronounced [u]. In Modern Greek Ω represents the same sound as omicron. Letter omega is transcribed ō or simply o.

Omega (the last letter of the Greek alphabet) is often used to denote the last, the end, or the ultimate limit of a set, in contrast to Alpha, the first letter of the Greek alphabet. In the New Testament book of Revelation, God is declared to be the "alpha and omega, the beginning and the end, the first and the last".^[3]

Omega was also adopted into the early Cyrillic alphabet. See omega (Cyrillic) (Ѡ, ѡ). A Raetic variant is at the origin of Elder Futhark ᛟ.

The upper-case letter Ω is used as a symbol, it is also used often outside its Greek alphabetical context in literature, advertising and other forms of human expression.

• For ohm — SI unit of electrical resistance; formerly also used upside down (℧) to represent mho, the old name for the inverse of an ohm (now siemens with symbol S) used for electrical conductance. Unicode has a separate code point for the ohm sign (U+2126, Ω), but it is only included for backwards compatibility and the Greek uppercase omega character (U+03A9, Ω) is preferred. ^[4]

• In computer science, in notation related to Big O notation to describe the asymptotic behavior of functions. See also Chaitin's constant
• In mathematics, the Omega constant, a solution of Lambert's W function; or the first uncountable ordinal number (also known as ω₁)
• In mathematics, Omega denotes Chaitin's constant.
• Also In mathematics, Omega denotes a 2-d region in calculus, usually corresponding to the domain of a double integral.
• In statistics, it is used as the symbol for the sample space, or total set of possible outcomes.
• In physics, the solid angle or the rate of precession in a gyroscope.
• In particle physics to represent the Omega baryons. A lowercase omega is used for the omega mesons.
• In combinatory logic, the looping combinator, (λ x. x x) (λ x. x x)
• In astronomy (cosmology) Ω refers to the density of the universe, also called the density parameter.
• Year or date of death

The lower-case letter ω is used as a symbol:

• In textual criticism, the archetype of a manuscript tradition
• In physics, angular velocity and angular frequency.
• In mathematics, the first transfinite ordinal number
• In number theory, an arithmetic function
• In combinatory logic, the self-application combinator, (λ x. x x)
• In computer science, in notation related to Big O notation, the asymptotically dominant nature of functions
• In astronomy, as a ranking of a star's brightness
• In particle physics to represent the omega meson
• In circuit analysis and signal processing to represent natural frequency, related to frequency f by ω = 2πf.
• In biochemistry to denote the carbon atom furthest from the carboxyl group of a fatty acid.
• Used in place of ん in Japanese typing shorthand.
• In relational database theory ω is used to represent NULL, a missing or inapplicable value.
• In phonology, for a prosodic (or phonological) word.
• In biochemistry, for one of the RNA Polymerase subunits.

1. ^ The Greek Alphabet
2. ^ Herbert Weir Smyth. A Greek Grammar for Colleges. §1
3. ^ Revelation 22:13, KJV, and see also 1:8, Greek ἐγὼ τὸ ἄλφα καὶ τὸ ὦ, ὁ πρῶτος καὶ ὁ ἔσχατος, ἡ ἀρχὴ καὶ τὸ τέλος. Or in Revelation 1:8 as seen in the Latin Vulgate Bible, the Greek is shown, surrounded by Latin: "ego sum α et ω principium et finis dicit Dominus Deus qui est et qui erat et qui venturus est Omnipotens"
4. ^ Excerpts from the The Unicode Standard, Version 4.0, accessed 11 October 2006