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

Example Sentences

Merger activity is starting to heat up again in the sector.

From Barron's • Apr. 6, 2026

Once activated, it sends signals that increase the activity of osteoblasts and reduce the activity of osteoclasts.

From Science Daily • Apr. 6, 2026

"We are seeing a gradual but important shift from places being understood mainly as seasonal visitor destinations, to places that can support year-round economic activity, social participation and knowledge exchange," he said.

From BBC • Apr. 6, 2026

“We’re seeing some expansion across the services economy with stronger business activity and new orders,” an executive at a professional firm was quotes as having told ISM.

From MarketWatch • Apr. 6, 2026

I nod along as Connor explains every single activity, every single trip and fall.

From "The Sea in Winter" by Christine Day

Related Words

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