activity

UK: /ækˈtɪvɪti/ US: /ækˈtɪvɪti/ ,(ak tiv′i tē)

Inflections of 'activity' (n): npl: activities

WordReference Random House Learner's Dictionary of American English © 2025

ac•tiv•i•ty /ækˈtɪvɪti/   n., pl. -ties. 

1. [uncountable] the state or quality of being active or lively.
2. a specific deed, action, or function:
   [countable] social activities.

WordReference Random House Unabridged Dictionary of American English © 2025

ac•tiv•i•ty  (ak tiv′i tē), n., pl. -ties. 

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, esp. 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. Chemistry [Physical Chem.] the capacity of a substance to react, corrected for the loss of reactivity due to the interaction of its constituents.
8. Physics
   • the number of atoms of a radioactive substance that disintegrate per unit of time, usually expressed in curies.
   • radioactivity.
9. an organizational unit or the function it performs.

• Medieval Latin āctīvitās. See active, -ity
• Middle French)
• (1520–30

Collins Concise English Dictionary © HarperCollins Publishers::

activity / ækˈtɪvɪtɪ/ noun ( -ties)

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. the capacity of a substance to undergo chemical change