deviation

Etymology

From Middle French deviation, from Medieval Latin deviatio. Morphologically deviate + -ion.

noun

1. The act of deviating; wandering off the correct or true path or road.
2. A departure from the correct way of acting.
3. The state or result of having deviated; a transgression; an act of sin; an error; an offense.
   mankind’s deviation from divine will
4. A detour in a road or railway.
5. (aviation) A detour to one side of the originally-planned flightpath (for instance, to avoid weather); the act of making such a detour.
   The flightcrew observed en route thunderstorms both visually and on the airplane's weather radar, so they requested and received clearance for a deviation to the left of course from the HNL Combined Center Radar Approach Control (CERAP). 18 March 1992, National Transportation Safety Board, “1.1 History of the Flight”, in Aircraft Accident Report: Explosive Decompression - Loss of Cargo Door in Flight, United Airlines Flight 811, Boeing 747-122, N4713U, Honolulu, Hawaii, February 24, 1989, page 2
6. (contract law) The voluntary and unnecessary departure of a ship from, or delay in, the regular and usual course of the specific voyage insured, thus releasing the underwriters from their responsibility.
7. (Absolute Deviation) The shortest distance between the center of the target and the point where a projectile hits or bursts.
8. (statistics) For interval variables and ratio variables, a measure of difference between the observed value and the mean.
9. (metrology) The signed difference between a value and its reference value.