noun

- the act of deviating.
- departure from a standard or norm.
- Statistics. the difference between one of a set of values and some fixed value, usually the mean of the set.
- Navigation. the error of a magnetic compass, as that of a ship, on a given heading as a result of local magnetism.Compare variation(def 8).
- Optics.
- Also called deflection.the bending of rays of light away from a straight line.
- angle of deviation.

- departure or divergence from an established dogma or ideology, especially a Communist one.

noun

- an act or result of deviating
- statistics the difference between an observed value in a series of such values and their arithmetic mean
- the error of a compass due to local magnetic disturbances

1640s, noun of action from deviate (v.). Statistical sense is from 1858. Related: Deviational.

n.

- A turning away or aside from a normal course.
- An abnormality.
- Deviant behavior or attitudes.
- The difference, especially the absolute difference, between one number in a set and the mean of the set.

- The difference between one number in a set and the mean of the set.