- The state or quality of being active; movement, action, operation.
- Something that a person or group does or has done.
From latin activus, from agere ("to d.o")
- The activity of the volcano could be monitored from the space.
- The children's activity center was filled with laughter and excitement.
- The company's activity in the field of renewable energy has grown significantly.
- The activity of the brain during sleep is not yet fully understood.
- The activity of the enzyme was measured in the lab.