activity

A1 · Beginner Countable noun

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

n. 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.”

C1 · Advanced Uncountable noun Science Technical

n. the speed at which a radioactive substance breaks down.

n. 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.”

C1 · Advanced Uncountable noun Science Technical

n. how easily a substance reacts with other chemicals.

n. 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.”

C2 · Proficiency Countable noun Science Technical · Academic

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

n. 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.”