activity

American  

[ak-tiv-i-tee] / ækˈtɪv ɪ ti /

noun

activities plural

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

Derived Forms

• preactivity
  noun
• superactivity
  noun
• nonactivity
  noun

Inflected Forms

noun

• activities
  plural

Etymology

Origin of activity

First recorded in 1520–30; from Middle French or directly from Medieval Latin āctīvitās; see 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

“When you have a guy that’s that serious about even considering coming out, it’s like ‘OK, we might have a chance,’” safety Quentin Lake said Monday after the Rams completed an organized-team activity workout.

From Los Angeles Times • Jun. 9, 2026

Using two-photon microscopy, the researchers monitored activity inside the animals' brains as they reacted to this surprising outcome.

From Science Daily • Jun. 8, 2026

Any activity that makes your muscles work harder than usual counts.

From BBC • Jun. 8, 2026

Saudi pricing is closely watched as a barometer of regional demand, with the latest cuts coming as China sharply reduced crude imports amid weaker refining activity and lower refined-product exports.

From The Wall Street Journal • Jun. 8, 2026

This is the kind of activity student government was born to do.

From "Linked" by Gordon Korman

Related Words

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