noun

• (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)."
• (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.
• (Absolute Deviation) The shortest distance between the center of the target and the point where a projectile hits or bursts.
• (statistics) For interval variables and ratio variables, a measure of difference between the observed value and the mean.