Source : Webster's Revised Unabridged Dictionary (1913)

Deviation \De`vi*a"tion\, n. [LL. deviatio: cf. F.
   d['e]viation.]
   1. The act of deviating; a wandering from the way; variation
      from the common way, from an established rule, etc.;
      departure, as from the right course or the path of duty.

   2. The state or result of having deviated; a transgression;
      an act of sin; an error; an offense.

Source : WordNet®

deviation
     n 1: a variation that deviates from the standard or norm; "the
          deviation from the mean" [syn: {divergence}, {departure},
           {difference}]
     2: the difference between an observed value and the expected
        value of a variable or function
     3: the error of a compass due to local magnetic disturbances
     4: deviate behavior [syn: {deviance}]
     5: a turning aside (of your course or attention or concern); "a
        diversion from the main highway"; "a digression into
        irrelevant details"; "a deflection from his goal" [syn: {diversion},
         {digression}, {deflection}, {deflexion}, {divagation}]