Definition of "deviation"

deviation

/diviˈeɪʃən/

noun
countable and uncountable, plural deviations
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.
4. A detour in a road or railway.
  Quotations
  "A rough place, my last district; sixty navvies on the Springbank deviation works, let alone eighty of these dole bugs to attend to."
  1938, Norman Lindsay, Age of Consent, 1st Australian edition, Sydney, N.S.W.: Ure Smith, published 1962, page 21
5. (aviation) A detour to one side of the originally-planned flightpath (for instance, to avoid weather); the act of making such a detour.
  Quotations
  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).
  1992 March 18, 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.