deviation

UK: /ˌdiːviˈeɪʃ^ən/ US: /ˌdiviˈeɪʃən/ ,(dē′vē ā′shən)

WordReference Random House Learner's Dictionary of American English © 2026

de•vi•a•tion /ˌdiviˈeɪʃən/   n. 

1. [uncountable] behavior that differs or departs from what is considered and accepted as normal or standard esp. with regard to sexual behavior.
2. an example of differing from what is expected;
   a change:
   [countable] Some deviations from the regular readings on the compass were due to the presence of metal objects.
See -via-.

WordReference Random House Unabridged Dictionary of American English © 2026

de•vi•a•tion  (dē′vē ā′shən), n. 

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. Nautical, Naval Terms [Navig.] the error of a magnetic compass, as that of a ship, on a given heading as a result of local magnetism. Cf. variation (def. 8).
5. Optics
   • Also called deflection. the bending of rays of light away from a straight line.
   • See angle of deviation. 
6. Government departure or divergence from an established dogma or ideology, esp. a Communist one.

• Medieval Latin dēviātiōn- (stem of dēviātiō), equivalent. to Late Latin dēviāt(us) (see deviate) + -iōn- -ion
• Middle French)
• 1375–1425; late Middle English (

de•vi•a•to•ry  (dē′vē ə tôr′ē, -tōr′ē), de′vi•a′tive, adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

deviation / ˌdiːvɪˈeɪʃən/ noun

1. an act or result of deviating
2. 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