# activity

/ækˈtɪvəti/ (US) · /æktˈɪvɪti/ (UK)

Source: https://englishreference.com/word/activity
Updated: 2026-05-01

## Senses

### 1. being busy

noun · CEFR A1

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

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

- There was a lot of activity in the kitchen as they prepared dinner.
- 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. a specific task or hobby

noun · CEFR A1

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

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

- The hotel offers many outdoor activities like hiking and swimming.
- 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.

### 3. radioactive decay

noun · CEFR C1 · Technical

the speed at which a radioactive substance breaks down.

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

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

### 4. chemical reactivity

noun · CEFR C1 · Technical

how easily a substance reacts with other chemicals.

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

- The activity of the metal changed when it was placed in the acid.
- The catalyst was chosen specifically to increase the chemical activity of the reagents without being consumed in the process.

### 5. grammar aspect

noun · CEFR C2 · Technical · Academic

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

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

- In the sentence 'he is running', the verb shows activity.
- The distinction between activity and accomplishment in lexical aspect is crucial for understanding how different languages handle temporal flow.

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

## Examples

- Swimming is my favorite physical activity.
- The teacher plans a different classroom activity for every day of the week to keep students engaged.
- While the city center is usually a hub of commercial activity, the streets remained strangely quiet during the unexpected holiday weekend.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.