1.any specific activity;
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