What is the meaning of activity?

noun

• Any specific behavior.
  • usage: "they avoided all recreational activity"
• The state of being active.
  • usage: "his sphere of activity"; "he is out of action"
  • synonyms: action, activeness
• An organic process that takes place in the body.
  • usage: "respiratory activity"
  • synonyms: bodily process, body process, bodily function
• Chemistry) the capacity of a substance to take part in a chemical reaction. (
  • usage: "catalytic activity"
• A process existing in or produced by nature (rather than by the intent of human beings. )
  • usage: "the action of natural forces"; "volcanic activity"
  • synonyms: natural process, natural action, action
• The trait of being active; moving or acting rapidly and energetically.
  • usage: "the level of activity declines with age"
  • synonyms: activeness