The lexical aspect (aktionsart) of verbs or predicates that change over time and have no natural end point.
Something done as an action or a movement.
Something done for pleasure or entertainment, especially one involving movement or an excursion.
The state or quality of being active; activeness.
The number of radioactive decays per unit time. Unit for it: becquerel or curie
The propery of substances to react with other substances
Something which amuses, and serves to make time pass agreeably.