# Omega (Greek letter)

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Omega (uppercase Ω, lowercase ω) is the 24th and last letter of the Greek alphabet.^{[1]} In the Greek numeric system, it has a value of 800.
Pronounced [ɔ:] or 'aw' as in 'r**aw'**.^{[2]}^{[3]}

## Symbol uppercase Ω

**Astronomy**

- Density of the universe, also referred to as the cosmological density parameter. with components of mass density, Ω
_{M}, and vacuum energy density, Ω_{L}.^{[4]}^{[5]}^{[6]}

**Chemistry**

- Designation for the last carbon on the chain in a fatty acid

**Electricity**

- Ohm: SI unit of electrical resistance
- Siemens (unit), abbreviated S, is the reciprocal of the ohm.

**Mathematics**

- Omega constant (Lambert’s W function)
^{[7]} - Chaitin’s constant: the probability that a randomly selected valid program string is interpreted by a halting

term^{[8]}

- Calculus: a 2-D region
- A theoretical measure of the execution of an algorithm, (e.g. required time or memory) given the problem size
*n*(e.g. the number of items).^{[9]} - Stochastic process
^{[10]}

**Meteorology**

- Used to designate vertical motion in the atmosphere
^{[11]}

**Statistics**

- Sample space
- Set of possible outcomes

**Literary**

- End or last thing in a series
^{[12]}

**Physics**

- Solid angle or rate of precession in a gyroscope
^{[13]} - Omega baryons (particle physics)
- Negatively charged elementary particle with a mass 3270 times the mass of an electron.
^{[14]} *Omega minus b*: a very short-lived unstable meson with mass 1532 times the mass of an electron (aka omega meson)^{[15]}

## Symbol lowercase ω

**Mathematics**

- The set of all natural numbers
^{[16]}

**Physics**

- Angular frequency

## References

- ↑ Greek Omniglot
- ↑ IPA pronunciation chart for English equivalentsGreek alphabet pronunciation and languageOmniglot
- ↑ Omega pronunciation Ancient Greek tutorials, UC Berkeley
- ↑ [1] Meteorite Book, Northern Arizona University
- ↑ Curvature Astrophysics
- ↑ Cosmological curvature Cosmology
- ↑ [2] Wolfram Math World
- ↑ [3] School of Computer Sciences, Carnegie Mellon University
- ↑ [4] National Institute of Standards and Technology
- ↑ Formal definition and basic properties Stochastic process
- ↑ [5] JetStream – Online school for weather, National Weather Service
- ↑ [6] Ask Oxford
- ↑ [7]Wolfram Math World
- ↑ [8] Merriam Webster Online
- ↑ [9] Merriam Webster Online
- ↑ Notation Natural number