Definition of Deviation

Noun: deviation ,dee-vee'ey-shun

A variation that deviates from the standard or norm
"the deviation from the mean";
- divergence, departure, difference
(statistics) 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 behaviour
- deviance, deviancy
A turning aside (of your course, attention or concern)
"a deviation from the main highway";
- diversion, digression, deflection, deflexion [Brit], divagation