Definition of activity:

• Work performed to create a result. Actions done to help ABC computations. The smallest task done in a time, in relation to others, resouces, and costs. AKA task.
• the state of being active; " his sphere of activity"; " he is out of action"
• the trait of being active; moving or acting rapidly and energetically; " the level of activity declines with age"
• ( chemistry) the capacity of a substance to take part in a chemical reaction; " catalytic activity"
• an organic process that takes place in the body; " respiratory activity"
• any specific activity; " they avoided all recreational activity"
• a process existing in or produced by nature ( rather than by the intent of human beings); " the action of natural forces"; " volcanic activity"
• The state or quality of being active; nimbleness; agility; vigorous action or operation; energy; active force; as, an increasing variety of human activities.
• Activeness.
• Energy; quickness in doing; the quality of doing promptly.
• Quality of being active; agility; operation.
• The quality of being active; action.

Usage examples for activity

1. Some authors deny its activity altogether; others admit a partial activity.  Modern Magic by Maximilian Schele de Vere

2. The army has a look of service and activity rather than of force.  Recollections of Europe by J. Fenimore Cooper

3. In an instant all was activity and excitement in the little camp.  Narratives of Shipwrecks of the Royal Navy; between 1793 and 1849 by William O. S. Gilly

4. At last ten o'clock came, bringing with it a sound which startled the near- by camp into activity.  The Iron Trail by Rex Beach