activity

noun

1. any specific behavior"they avoided all recreational activity"
2. the state of being active"his sphere of activity"
3. an organic process that takes place in the body"respiratory activity"
4. (chemistry) the capacity of a substance to take part in a chemical reaction"catalytic activity"
5. a process existing in or produced by nature (rather than by the intent of human beings)"the action of natural forces"
6. the trait of being active; moving or acting rapidly and energetically"the level of activity declines with age"