1. any specific behavior

- they avoided all recreational activity

Definition categories: act, deed

2. the state of being active

- his sphere of activity

- he is out of action

Similar word(s): action, activeness

Definition categories: state

3. an organic process that takes place in the body

- respiratory activity

Definition categories: process

4. (chemistry) the capacity of a substance to take part in a chemical reaction

- catalytic activity

Definition categories: state, capability, capacity

5. a process existing in or produced by nature (rather than by the intent of human beings)

- the action of natural forces

- volcanic activity

Similar word(s): action

Definition categories: process

6. the trait of being active; moving or acting rapidly and energetically

- the level of activity declines with age

Similar word(s): activeness

Definition categories: attribute, trait

Sentences with activity as a noun:

- Pit row was abuzz with activity.

- The activity for the morning was a walk to the store.

- Quilting can be an enjoyable activity.