deviation

American  

[dee-vee-ey-shuhn] / ˌdi viˈeɪ ʃən /

noun

1. the act of deviating.

2. departure from a standard or norm.

3. Statistics. the difference between one of a set of values and some fixed value, usually the mean of the set.

4. Navigation. the error of a magnetic compass, as that of a ship, on a given heading as a result of local magnetism.

5. Optics.

   1. Also called deflection.  the bending of rays of light away from a straight line.

   2. angle of deviation.

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

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deviation British  

/ ˌdiːvɪˈeɪʃən /

noun

1. an act or result of deviating

2. statistics the difference between an observed value in a series of such values and their arithmetic mean

3. the error of a compass due to local magnetic disturbances

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deviation Scientific  

/ dē′vē-ā′shən /

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

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Other Word Forms

Derived Forms

• deviatory
  adjective
• deviative
  adjective
• nondeviation
  noun

Etymology

Origin of deviation

First recorded in 1375–1425; late Middle English, from Middle French, from Medieval Latin dēviātiōn-, stem of dēviātiō; equivalent to deviate + -ion

Explanation

Anything that varies from the accepted norm or standard is called a deviation. It is common in math and science, but it can refer to anything that differs from the expected. Deviation in nature is an important part of evolution. When something causes a creature’s DNA to change, it creates a deviation, or a changed characteristic. If the deviation makes the organism better able to survive, it passes the change on to its descendants. People are naturally given to change, so there are deviations in critical thought as well as in math and science. Those deviations often account for the creativity that gives rise to new ideas, or theories, or even musical styles.

Example Sentences

It’s the first real deviation from the dead-eyed cycle of his daily life since his wife grabbed her car keys and never looked back.

From Salon • May 30, 2026

This tiny deviation is known as the "anomalous magnetic moment," or g−2.

From Science Daily • May 19, 2026

In that scenario, the jury would have to determine whether Microsoft -- the then-startup's first private investor with a $13 billion injection -- knowingly facilitated the company's deviation from its original mission.

From Barron's • May 14, 2026

Restaurant tipping rates decreased by 0.05% on weekends when box-office revenue was one standard deviation higher than average.

From The Wall Street Journal • May 9, 2026

That is just ordinary deviation from external reality.

From "East of Eden" by John Steinbeck

Related Words

• aberration
• alteration
• anomaly
• breach
• detour
• discrepancy
• disparity
• divergence
• diversion
• fluctuation
• inconsistency
• irregularity
• modification
• variance
• variation