"Ω" redirects here. For the unit of electrical resistance, see Ohm.This article is about the Greek letter. For the Cyrillic letter, see Omega (Cyrillic). For the Latin letter, see Latin omega.For other uses, see Omega (disambiguation).Not to be confused with the Canadian Aboriginal syllabic ᘯ.
As the final letter in the Greek alphabet, omega 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, as in the phrase Alpha and Omega.
History
The letter Ω was not part of the early Greek alphabets in the 8th century BC. It was introduced in the late 7th century BC in the Ionian cities of Asia Minor to denote a longopen-mid back rounded vowel[ɔː]. It is a variant of omicron (Ο), broken up at the side (), with the edges subsequently turned outward (, , , ). The Dorian city of Knidos as well as a few Aegean islands, namely Paros, Thasos and Melos, chose the exact opposite innovation, using a broken-up circle for the short and a closed circle for the long /o/.
The name Ωμέγα is Byzantine; in Classical Greek, the letter was called ō (ὦ) (pronounced /ɔ̂ː/), whereas the omicron was called ou (οὖ) (pronounced /ôː/). 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 flattened-out form of the letter () that had its edges curved even further upward.
Omega was also adopted into the Latin alphabet, as the Latin omega, as a letter of the 1982 revision to the African reference alphabet, and is in sparse use.
The symbol Ω (uppercase letter)
Plaque on the Greek island of Kos with "underlined O" form of omega
For oxygen-18, a natural, stable isotope of oxygen.
For omega loop, a protein structural motif consisting of a loop of six or more amino acid residues in any sequence, a structure named for its resemblance to the Greek letter.
For ohm – SI unit of electrical resistance. Unicode has a separate code point U+2126ΩOHM SIGN (HTML entityΩ), but it is included only for backward compatibility, and the canonically equivalent code point U+03A9ΩGREEK CAPITAL LETTER OMEGA (Ω) is preferred. Also formerly also used upside down (U+2127℧INVERTED OHM SIGN) to represent mho, the old name for the inverse of an ohm (now siemens with symbol S), the SI unit of electrical conductance.
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.
A secret boss in the Final Fantasy series called Omega ( Ω ) Weapon.
A character from the series Doctor Who called Omega, believed to be one of the creators of the Time Lords of Gallifrey.
The symbol for the highest power level of a PSI attack in the Mother/EarthBound games.
A symbol used by U.S. citizens in the 1960s & 1970s to denote resistance to the U.S. war in Viet Nam. Adapted from the SI unit for electrical resistance.
U+03A9ΩGREEK CAPITAL LETTER OMEGA (Ω, Ω)
U+03C9ωGREEK SMALL LETTER OMEGA (ω)
U+03D6ϖGREEK PI SYMBOL (ϖ, ϖ)
U+0460ѠCYRILLIC CAPITAL LETTER OMEGA
U+0461ѡCYRILLIC SMALL LETTER OMEGA
U+047AѺCYRILLIC CAPITAL LETTER ROUND OMEGA
U+047BѻCYRILLIC SMALL LETTER ROUND OMEGA
U+2375⍵APL FUNCTIONAL SYMBOL OMEGA
U+2379⍹APL FUNCTIONAL SYMBOL OMEGA UNDERBAR
U+2CB0ⲰCOPTIC CAPITAL LETTER OOU
U+2CB1ⲱCOPTIC SMALL LETTER OOU
U+2CBEⲾCOPTIC CAPITAL LETTER OLD COPTIC OOU
U+2CBFⲿCOPTIC SMALL LETTER OLD COPTIC OOU
U+A64CꙌCYRILLIC CAPITAL LETTER BROAD OMEGA
U+A64DꙍCYRILLIC SMALL LETTER BROAD OMEGA
U+A67B◌ꙻCOMBINING CYRILLIC LETTER OMEGA
U+A7B6ꞶLATIN CAPITAL LETTER OMEGA
U+A7B7ꞷLATIN SMALL LETTER OMEGA
U+A7DDLATIN CAPITAL LETTER CLOSED OMEGA
U+AB65ꭥGREEK LETTER SMALL CAPITAL OMEGA
U+107A4𐞤MODIFIER LETTER SMALL CLOSED OMEGA
U+1D6C0𝛀MATHEMATICAL BOLD CAPITAL OMEGA
U+1D6DA𝛚MATHEMATICAL BOLD SMALL OMEGA
U+1D6FA𝛺MATHEMATICAL ITALIC CAPITAL OMEGA
U+1D714𝜔MATHEMATICAL ITALIC SMALL OMEGA
U+1D734𝜴MATHEMATICAL BOLD ITALIC CAPITAL OMEGA
U+1D74E𝝎MATHEMATICAL BOLD ITALIC SMALL OMEGA
U+1D76E𝝮MATHEMATICAL SANS-SERIF BOLD CAPITAL OMEGA
U+1D788𝞈MATHEMATICAL SANS-SERIF BOLD SMALL OMEGA
U+1D7A8𝞨MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL OMEGA
U+1D7C2𝟂MATHEMATICAL SANS-SERIF BOLD ITALIC SMALL OMEGA
U+1DF53LATIN SMALL LETTER BARRED CLOSED OMEGA
U+1DF60LATIN SMALL LETTER OMEGA WITH LOOP
U+1DF74LATIN CAPITAL LETTER CLOSED OMEGA WITH LONG STEM
U+1DF75LATIN SMALL LETTER CLOSED OMEGA WITH LONG STEM
U+1DF76LATIN CAPITAL LETTER TURNED CLOSED OMEGA
U+1DF77LATIN SMALL LETTER TURNED CLOSED OMEGA
U+1DFF4MODIFIER LETTER SMALL GREEK OMEGA
↑The mathematical characters are used only in math. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate the style of the text.
12Anne Jeffery (1961), The Local Scripts of Archaic Greece, pp. 37–38.
↑Herbert Weir Smyth A Greek Grammar for Colleges §1.
↑Edward M. Thompson (1912), Introduction to Greek and Latin Paleography, Oxford: Clarendon, p. 144.
↑Capilla, José E.; Arevalo, Javier Rodriguez; Castaño, Silvino Castaño; Teijeiro, María Fé Díaz; del Moral, Rut Sanchez; Diaz, Javier Heredia (19 September 2012). "Mapping Oxygen-18 in Meteoric Precipitation over Peninsular Spain Using Geostatistical Tools"(PDF). cedex.es. Valencia, Spain: Ninth Conference on Geostatistics for Environmental Applications. Archived from the original(PDF) on 23 September 2015. Retrieved 8 May 2017.
↑Weisstein, Eric W. "Solid Angle". mathworld.wolfram.com. Retrieved 7 February 2025. The solid angle Ω subtended by a surface S is defined as the surface area Ω of a unit sphere covered by the surface's projection onto the sphere.
12"Frequently Asked Questions (FAQs)". ssd.jpl.nasa.gov. Archived from the original on 29 July 2025. Retrieved 25 September 2025. The point S represents the sun, P represents perihelion, i is the inclination, lower case omega (ω) is the argument of perihelion, and upper case omega (Ω) is the longitude of the ascending node.
↑Weisstein, Eric W. "Omega Constant". mathworld.wolfram.com. Retrieved 18 January 2025.
↑Weisstein, Eric W. "Brocard Points". mathworld.wolfram.com. Retrieved 7 February 2025.
↑Weisstein, Eric W. "Prime Factor". mathworld.wolfram.com. Retrieved 12 August 2020.
↑Weisstein, Eric W. "Big-Omega Notation". mathworld.wolfram.com. Retrieved 25 September 2025.
↑Weisstein, Eric W. "Chaitin's Constant". mathworld.wolfram.com. Retrieved 25 September 2025.
↑"Emblem of the Supreme Court - Herald Art". Herald Art. 7 May 2022. Retrieved 8 February 2025. The emblem shows the plant badges of England and Wales, Scotland and Northern Ireland surrounded by Omega the ultimate letter in the Greek alphabet.
↑"Desde la Revolución hasta el 2020". Gobierno de Aguascalientes. Retrieved 7 August 2024. ...su fachada representa a una omega que simboliza el final de la vida.
↑"6 Ridiculous Sci-Fi Energy Schemes". Popular Mechanics. 16 October 2013. Retrieved 7 February 2025. But the writers of one episode of Star Trek: Voyager apparently slept through that lecture, as they introduced the omega particle in "The Omega Directive."
↑Elert, Glenn (2023), "Special Symbols", The Physics Hypertextbook, hypertextbook, retrieved 1 February 2025, ω angular frequency
↑Elert, Glenn (2023), "Special Symbols", The Physics Hypertextbook, hypertextbook, retrieved 1 February 2025, ω, ω rotational velocity, rotational speed
↑Flanders, Tony (2 February 2007). "The Greek Alphabet". Sky & Telescope. Retrieved 25 September 2025. Stars within a constellation are usually lettered from Alpha (α) to Omega (ω) roughly in order of brightness, but there are numerous exceptions.
↑Weisstein, Eric W. "Ordinal Number". mathworld.wolfram.com. Retrieved 18 January 2025. The first transfinite ordinal, denoted ω, is ...
↑Easwaran, Kenny; Hájek, Alan; Mancosu, Paolo; Oppy, Graham (2024), "Infinity", in Zalta, Edward N.; Nodelman, Uri (eds.), The Stanford Encyclopedia of Philosophy (Summer 2024ed.), Metaphysics Research Lab, Stanford University, retrieved 7 February 2025
↑Weisstein, Eric W. "Wright Function". mathworld.wolfram.com. Retrieved 18 January 2025.
↑Weisstein, Eric W. "Distinct Prime Factors". mathworld.wolfram.com. Retrieved 8 February 2025. The distinct prime factors of a positive integer n>=2 are defined as the ω(n) numbers p_1, ..., p_(ω(n))...
↑Weisstein, Eric W. "Brocard Angle". mathworld.wolfram.com. Retrieved 7 February 2025.
↑Weisstein, Eric W. "Clique". mathworld.wolfram.com. Retrieved 7 February 2025. A clique of a graph G is a complete subgraph of G, and the clique of largest possible size is referred to as a maximum clique (which has size known as the (upper) clique number?(G)).
↑"Life Table — Solving Actuarial Math with Python". actuarialmath-guide.readthedocs.io. Retrieved 8 February 2025. A life table, from some initial age x0 to a maximum age ω, represents a survival model with probabilities...