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; see Alpha and Omega.
Ω was not part of the early (8th century BC) Greek alphabets. 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 (, , , ).[3]
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/.[3]
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/).[4]
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.[5]
Omega was also adopted into the Latin alphabet, as a letter of the 1982 revision to the African reference alphabet. It's in sparse use (see Latin omega).
For oxygen-18, a natural, stable isotope of oxygen[6]
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.[7]
For ohm – SI unit of electrical resistance;[8] 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 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.[9]
In statistical mechanics, Ω refers to the multiplicity (number of microstates) in a system.
The solid angle[10] 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.[20]
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
^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.
^ abAnne Jeffery (1961), The local scripts of archaic Greece, p.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.
^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.
^"Emblem of the Supreme Court - 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."
^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), Zalta, Edward N.; Nodelman, Uri (eds.), "Infinity", The Stanford Encyclopedia of Philosophy (Summer 2024 ed.), 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...