What is the meaning of deviation?

noun

• A variation that deviates from the standard or norm.
  • usage: "the deviation from the mean"
  • synonyms: divergence, departure, difference
• The difference between an observed value and the expected value of a variable or function.
• The error of a compass due to local magnetic disturbances.
• Deviate behavior.
  • synonyms: deviance
• A turning aside (of your course or attention or concern. )
  • usage: "a diversion from the main highway"; "a digression into irrelevant details"; "a deflection from his goal"
  • synonyms: diversion, digression, deflection, deflexion, divagation