Omega
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Greek alphabet  

Αα  Alpha  Νν  Nu 
Ββ  Beta  Ξξ  Xi 
Γγ  Gamma  Οο  Omicron 
Δδ  Delta  Ππ  Pi 
Εε  Epsilon  Ρρ  Rho 
Ζζ  Zeta  Σσς  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 
History  
Archaic local variants  
In other languages  
Scientific symbols  

Omega (capital: Ω, lowercase: ω; Greek Ωμέγα) 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{{#invoke:Category handlermain}}), whereas the omicron was called ou (οὖ{{#invoke:Category handlermain}}).^{[2]} The form of the uppercase letter derives from that of an omicron (Ο) broken up at the side (), with the edges subsequently turned outward (, , ).^{[3]} The modern lowercase shape goes back to the uncial form , a form that developed during the 3rd century BC in ancient handwriting on papyrus, from a flattenedout form of the letter () that had its edges curved even further upward.^{[4]}
In phonetic terms, the Ancient Greek Ω is a long openmid o [ɔː], comparable to the vowel of British English raw. In Modern Greek, Ω represents the same sound as omicron. The 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.
Omega was also adopted into the early Cyrillic alphabet. See Cyrillic omega (Ѡ, ѡ). A Raetic variant is conjectured to be at the origin or parallel evolution of the Elder Futhark ᛟ.
Omega was also adopted into the Latin alphabet, as a letter of the 1982 revision to the African reference alphabet. It has had little use. See Latin omega.
Omega is also used in Christianity, as a part of the Alpha and Omega metaphor.
The symbol Ω (uppercase letter)
Template:Refimprove section The uppercase letter Ω is used as a symbol:
 In chemistry:
 For oxygen18, a natural, stable isotope of oxygen.^{[5]}
 In physics:
 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 included only for backward compatibility, and the Greek uppercase omega character (U+03A9, Ω) is preferred.^{[6]}
 In statistical mechanics, Ω refers to the multiplicity (number of microstates) in a system.
 The solid angle or the rate of precession in a gyroscope.
 In particle physics to represent the Omega baryons.
 In astronomy (cosmology), Ω refers to the density of the universe, also called the density parameter.
 In astronomy (orbital mechanics), Ω refers to the longitude of the ascending node of an orbit
 In mathematics and computer science:
 In complex analysis, the Omega constant, a solution of Lambert's W function
 A variable for a 2dimensional region in calculus, usually corresponding to the domain of a double integral.
 In topos theory, the (codomain of the) subobject classifier of an elementary topos.
 In combinatory logic, the looping combinator, (λ x. x x) (λ x. x x)
 In group theory, the omega and agemo subgroups of a pgroup, Ω(G) and ℧(G)
 In statistics, it is used as the symbol for the sample space, or total set of possible outcomes.
 In number theory, Ω(n) is the number of prime divisors of n.
 in notation related to Big O notation to describe the asymptotic behavior of functions.
 Chaitin's constant.
 As part of logo or trademark:
 The logo of Omega Watches SA.
 Part of the Badge of the Supreme Court of the United Kingdom.
 Part of the mission patch for STS135, as it was the last mission of the Space Shuttle program.
 The logo of the God of War video game series based around Greek mythology.
 The logo of E123 Omega, a Sonic the Hedgehog character.
 The logo of the Heroes of Olympus series, based on Greek mythology.
 the logo of the Ultramarines in Warhammer 40,000
 The logo of Primal Groudon, the version mascot of Pokémon Omega Ruby.
 Other
 The symbol of the resistance movement against the Vietnamera draft
 Year or date of death
 Used to refer to the lowestranked wolf in a pack
 In eschatology, the symbol for the end of everything
 In molecular biology, the symbol is used as shorthand to signify a genetic construct introduced by a twopoint crossover
The symbol ω (lower case letter)
The minuscule letter ω is used as a symbol:
 Biochemistry and chemistry:
 Denotes the carbon atom furthest from the carboxyl group of a fatty acid.
 In biochemistry, for one of the RNA Polymerase subunits.
 In biochemistry, for the dihedral angle associated with the peptide group, involving the backbone atoms CαC'NCα
 In genomics, as a measure of evolution at the protein level (also denoted as d_{N}/d_{S} or K_{a}/K_{s} ratio).
 Physics
 angular velocity or angular frequency
 Computational fluid dynamics: the specific turbulence dissipation rate
 In meteorology, the change of pressure with respect to time of a parcel of air.
 In circuit analysis and signal processing to represent natural frequency, related to frequency f by ω = 2πf
 In astronomy, as a ranking of a star's brightness within a constellation
 In astronomy (orbital mechanics), as designation of the argument of periapsis of an orbit
 In particle physics to represent the omega meson
 Computer science:
 In notation related to Big O notation, the asymptotically dominant nature of functions
 In relational database theory to represent NULL, a missing or inapplicable value.
 Mathematics:
 The first transfinite ordinal number, often identified with the set of natural numbers including 0 (sometimes written )
 In set theory, the first uncountable ordinal number (more commonly written as ω_{1})
 The complex cube roots of 1
 The Wright Omega function
 A generic differential form
 In number theory, ω(n) is the number of distinct prime divisors of n.
 In number theory, an arithmetic function
 In combinatory logic, the selfapplication combinator, (λ x. x x)
 In mathematical/options finance, the elasticity of financial options
 In analytical investment management, the tracking error of an investment manager
 Other:
 Used in place of ん in Japanese typing shorthand.
 In linguistics, the phonological word
 In textual criticism, the archetype of a manuscript tradition
 In sociology, used to refer to the lowest ranking member of a group
Character Encodings
 Greek Omega / Coptic Oou
Template:Charmap ^{[7]}
 Cyrillic Omega
 Latin / IPA Omega
 Technical Omega symbols
 Mathematical Omega
These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.
Notes
 ↑ The Greek Alphabet
 ↑ Herbert Weir Smyth. A Greek Grammar for Colleges. §1
 ↑ Anne Jeffery (1961), The local scripts of archaic Greece, p.37–38.
 ↑ Edward M. Thompson (1912), Introduction to Greek and Latin paleography, Oxford: Clarendon. p.144
 ↑ http://www.cedex.es/NR/rdonlyres/B8A9522A5D6F4675921A24BB8458187B/124720/Capilla_et_al_geoENV_2012_Valencia_Espa%C3%B1a_Extended.pdf
 ↑ Excerpts from The Unicode Standard, Version 4.0. Retrieved 11 October 2006.
 ↑ Unicode Code Charts: Greek and Coptic (Range: 037003FF)