parity

¹ American  

[par-i-tee] / ˈpær ɪ ti /

noun

1. equality, as in amount, status, or character.

2. equivalence; correspondence; similarity; analogy.

   She and her brother always seemed like day and night to me, but I'm starting to see a real parity of nature between them.

3. Finance.

   1. equivalence in value in the currency of another country.

   2. equivalence in value at a fixed ratio between moneys of different metals.

4. Physics.

   1. a property of a wave function, expressed as +1 or −1 and noting the relation of the given function to the function formed when each variable is replaced by its negative, +1 indicating that the functions are identical and −1 that the second function is the negative of the first.

   2. Also called intrinsic parity.  a number +1 or −1 assigned to each kind of elementary particle in such a way that the product of the parities of the particles in a system of particles multiplied by the parity of the wave function describing the system is unchanged when particles are created or annihilated.

5. a system of regulating prices of farm commodities, usually by government price supports, to provide farmers with the same purchasing power they had in a selected base period.

6. Computers. the condition of the number of items in a set, particularly the number of bits per byte or word, being either even or odd: used as a means for detecting certain errors.

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parity ² American  

[par-i-tee] / ˈpær ɪ ti /

noun

Obstetrics.

1. the condition or fact of having borne offspring.

2. para.

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parity ¹ British  

/ ˈpærɪtɪ /

noun

1. the condition or fact of having given birth

2. the number of children to which a woman has given birth

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parity ² British  

/ ˈpærɪtɪ /

noun

1. equality of rank, pay, etc

2. close or exact analogy or equivalence

3. finance

   1. the amount of a foreign currency equivalent at the established exchange rate to a specific sum of domestic currency

   2. a similar equivalence between different forms of the same national currency, esp the gold equivalent of a unit of gold-standard currency

4. equality between prices of commodities or securities in two separate markets

5. physics

   1. a property of a physical system characterized by the behaviour of the sign of its wave function when all spatial coordinates are reversed in direction. The wave function either remains unchanged ( even parity ) or changes in sign ( odd parity )

   2.  P.  a quantum number describing this property, equal to +1 for even parity systems and –1 for odd parity systems See also conservation of parity

6. maths a relationship between two integers. If both are odd or both even they have the same parity; if one is odd and one even they have different parity

7. (in the US) a system of government support for farm products

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parity Scientific  

/ păr′ĭ-tē /

1. The property of a physical system that entails how the system would behave if the coordinate system were reversed, each dimension changing sign from x, y, z to −x, −y, −z. If a system behaves in the same way when the coordinate system is reversed, then it is said to have even parity; if it does not, it is said to have odd parity. For bosons, the antiparticle of any given particle has the same parity, odd or even, as that particle. For fermions, the antiparticle has the opposite parity.

2. See also conservation law parity conjugation

3. A quantum number, either +1 or −1, that mathematically describes this property.

4. The number of 1's in a piece of binary code, generally taken as the quality of odd or even rather than as a specific number. The parity of packets of binary data is often transmitted along with the data to help detect whether the value of any bits has been altered.

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Etymology

Origin of parity¹

First recorded in 1565–75; from French parité, and Late Latin paritāt- (stem of paritās “equality”); see par ¹, -ity

Origin of parity²

First recorded in 1875–80; from Latin par(ere) “to bring forth, bear” + -ity; see also -parous ( def. ), parent

Explanation

All things being equal, parity means, basically, equality. It’s used in finance, physics, math, and even sports. When people talk about parity in a football league, for example, they mean the teams are evenly matched. Go, evenly matched team, go! Parity comes from the same Latin root as pair, which is par, for “equal.” Parity is an equal amount of something, or an equal rank or skill level between people or teams. During the Cold War, the word parity was used to describe the equal amount of resources the US and the USSR had. So now it also means an equal amount between enemies, which is probably why sportscasters love it.

Example Sentences

Active management allows He and his three co-managers to deviate from risk parity if the team favors a particular asset class.

From Barron's • May 13, 2026

The Sacramento Kings, the kind of small-market team a salary cap is intended to lift toward parity, have made the playoffs once in the past 20 seasons.

From Los Angeles Times • May 12, 2026

Defenders of mental-health parity argue that spending and diagnoses are rising to meet previously unmet needs.

From The Wall Street Journal • May 10, 2026

“If Intel’s view of CPU-to-GPU reaching parity with agents proves right, we think that can help elongate the memory cycle,” Sankar said.

From MarketWatch • Apr. 28, 2026

Maybe it meant that parity had been reached, that tonight was the night for the west side of Odessa to reach back into history, to show that it too could excel at what mattered most.

From "Friday Night Lights: A Town, A Team, And A Dream" by H.G. Bissinger

Related Words

• consistency
• uniformity
• unity