(physics) the idea that the laws of physics should remain the same if to switch left and right or up and down

(computer) an extra bit added to a binary code to ensure the accuracy of data transmission or storage

(mathematics) a relation between a pair of integers: if both integers are odd or both are even they have the same parity; if one is odd and the other is even they have different parity

(obstetrics) the number of liveborn children a woman has delivered