activity

American  

[ak-tiv-i-tee] / ækˈtɪv ɪ ti /

noun

plural

activities

1. the state or quality of being active.

   There was not much activity in the stock market today. He doesn't have enough physical activity in his life.

2. a specific deed, action, function, or sphere of action.

   social activities.

3. work, especially in elementary grades at school, that involves direct experience by the student rather than textbook study.

4. energetic activity; animation; liveliness.

5. a use of energy or force; an active movement or operation.

6. normal mental or bodily power, function, or process.

7. Physical Chemistry. the capacity of a substance to react, corrected for the loss of reactivity due to the interaction of its constituents.

8. Physics.

   1. the number of atoms of a radioactive substance that disintegrate per unit of time, usually expressed in curies.

   2. radioactivity.

9. an organizational unit or the function it performs.

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activity British  

/ ækˈtɪvɪtɪ /

noun

1. the state or quality of being active

2. lively action or movement

3. any specific deed, action, pursuit, etc

   recreational activities

4. the number of disintegrations of a radioactive substance in a given unit of time, usually expressed in curies or disintegrations per second

5. 1. the capacity of a substance to undergo chemical change

   2. the effective concentration of a substance in a chemical system. The absolute activity of a substance B, λ B , is defined as exp (μ B RT ) where μ B is the chemical potential

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Other Word Forms

• nonactivity noun
• preactivity noun
• superactivity noun

Etymology

Origin of activity

First recorded in 1520–30; from Middle French or directly from Medieval Latin āctīvitās; active, -ity

Explanation

An activity is something you do, or just the state of doing. You might plan some indoor activities for a rainy day, or you might just rely on watching your gerbils' activity in their cage. Usually, when you use an article like an or the in front of activity, you are referring to a specific event. For example, you might search for the best activity on the cruise ship to fill your afternoon — shuffleboard, anyone? If you take the article away, and you refer to activity, you are usually referring to action. If there is too much activity on the cruise ship dance floor, you might want to avoid that zone.

Example Sentences

Once conditions improve, these structures break apart and normal cellular activity resumes.

From Science Daily • Apr. 12, 2026

Passed in 2010, the law deemed them to be vital water reserves, and so prohibited any damaging commercial activity.

From BBC • Apr. 10, 2026

Copper prices are highly correlated to economic activity.

From Barron's • Apr. 10, 2026

The survey’s future drilling and business activity index, which covers expectations for the next six months, rises to 25 in the quarter from minus 19 in the fourth quarter.

From The Wall Street Journal • Apr. 10, 2026

The purpose of this letter is to inform you that the performance of your agreement with a corporate sponsor in Yugoslavia to play chess is deemed to be in support of that sponsor's commercial activity.

From "Endgame" by Frank Brady

Related Words

• act
• endeavor
• enterprise
• job
• project
• scheme
• task
• venture
• work