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activity

US //ækˈtɪvəti// UK //æktˈɪvɪti// ac·tiv·i·ty
  1. 1 being busy (n.)
    A1 Beginner

    a situation where a lot of things are happening or people are moving around.

    the state or quality of being active; a condition of constant or energetic movement.

    Example

    There was a lot of activity in the kitchen as they prepared dinner.

    Example

    The sudden burst of activity in the lobby suggested that the guest of honour had finally arrived for the gala.

    Usage

    Often uncountable when referring to general movement in a place.
  2. 2 a specific task or hobby (n.)
    A1 Beginner

    something that you do for a particular purpose, like a hobby or a school task.

    a specific deed, action, or pursuit, especially one organized for education or recreation.

    Example

    The hotel offers many outdoor activities like hiking and swimming.

    Example

    The teacher designed a classroom activity that required students to collaborate on a complex problem-solving task.

    Usage

    Countable; frequently used in the plural to describe a range of options.
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  1. 3 radioactive decay (n.)
    C1 Advanced Technical Science

    the speed at which a radioactive substance breaks down.

    the number of nuclear decays occurring in a radioactive sample per unit time.

    Example

    The scientist measured the activity of the sample to see if it was safe.

    Example

    The laboratory monitored the residual activity of the isotopes to ensure they had decayed below the safety threshold before disposal.

    Usage

    Measured in becquerels or curies.
  2. 4 chemical reactivity (n.)
    C1 Advanced Technical Science

    how easily a substance reacts with other chemicals.

    the property or tendency of a substance to undergo a chemical reaction with other substances.

    Example

    The activity of the metal changed when it was placed in the acid.

    Example

    The catalyst was chosen specifically to increase the chemical activity of the reagents without being consumed in the process.
  3. 5 grammar aspect (n.)
    C2 Proficiency Technical Academic Science

    a type of verb that describes an action that continues and has no natural end.

    a lexical aspect of verbs describing situations that involve internal change and lack a built-in terminal point.

    Example

    In the sentence 'he is running', the verb shows activity.

    Example

    The distinction between activity and accomplishment in lexical aspect is crucial for understanding how different languages handle temporal flow.

    Teacher's tip

    This is a highly specialized term in linguistics; learners will usually encounter 'continuous' or 'progressive' instead.
Origin

From Middle French activité, from Latin activitas. Equivalent to active + -ity.

Idioms1 entry

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