Behaviour or Behavior | Meaning, Spelling & Examples

Behaviour and behavior are two different spellings of the noun referring to the way a person, animal, other organism, or machine acts or functions. It’s related to the verb “behave” meaning “conduct oneself” or “act.”

The spelling varies depending on whether you’re using UK or US English:

  • In UK English, “behaviour” (with a “u”) is standard.
  • In US English, “behavior” (with no “u”) is the correct spelling.
    Examples: Behaviour and behavior in a sentence
    The school does not tolerate bullying or other forms of anti-social behaviour/behavior.

    Ever since he broke the vase, Gus has been on his best behaviour/behavior.

    Jordan’s research focuses on the relationship between empathy and criminal behaviour/behavior.

    As of yet, little is known about the behaviour/behavior of the virus.

    Many words that end in “-our” in UK English end in “-or” in US English. Some other common examples include “favour/favor,” “colour/color,” “honour/honor,” and “flavour/flavor.”

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    Behavioural vs. behavioral

    The regional spelling distinction carries over to related forms of the words, including the adjective “behavioural/behavioral” and the adverb “behaviourally/behaviorally.”

    • In UK English, “behavioural” and “behaviourally” are correct.
    • In US English, “behavioral” and “behaviorally” are standard.
        Examples: Other forms of “behaviour/behavior” in a sentence
        Kayla is studying to become a behavioural/behavioral psychologist.

        Research has found that human infants and ape infants are behaviourally/behaviorally similar.

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        Best behaviour or best behavior

        Best behaviour/best behavior is part of the expression “be on your best behaviour/behavior,” meaning “behave very well.” The possessive determiner used in the expression varies depending on the person being referred to. The spelling distinction also applies to this phrase.

            Examples: “Best behaviour/best behavior” in a sentence
            The principal has asked students to be on their best behaviour/best behavior during the school inspection.

            Anthony is on his best behaviour/best behavior because he has his employee review next week.

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            Eoghan Ryan

            Eoghan has a lot of experience with theses and dissertations at bachelor's, MA, and PhD level. He has taught university English courses, helping students to improve their research and writing.