par·i·ty 1 
(părĭ-tē)
(părĭ-tē)n. pl. par·i·ties
1. Equality, as in amount, status, or value.
2. Functional equivalence, as in the weaponry or military strength of adversaries: "A problem that has troubled the U.S.-Soviet relationship from the beginning has been the issue of parity" (Charles William Maynes).
3. The equivalent in value of a sum of money expressed in terms of a different currency at a fixed official rate of exchange.
4. Equality of prices of goods or securities in two different markets.
5. A level for farm-product prices maintained by governmental support and intended to give farmers the same purchasing power they had during a chosen base period.
6. Mathematics The even or odd quality of an integer. If two integers are both odd or both even, they are said to have the same parity; if one is odd and one even, they have different parity.
7. Abbr. P Physics
a. An intrinsic symmetry property of a physical system, such as a subatomic particle, that specifies how the system would behave if the three spatial coordinates were reversed from x, y, z to -x, -y, -z.
b. A quantum number, either +1 (even) or -1 (odd), that mathematically represents this property.
8. Computers
a. The even or odd quality of the number of 1's or 0's in a binary code, often used to determine the integrity of data especially after transmission.
b. A parity bit.
[French parité, from Old French parite, from Late Latin paritās, from pār, par-, equal; see PAIR.]