activity

(noun) any specific behavior. Examples: "They avoided all recreational activity."

(noun) the state of being active. Synonyms: action, activeness. Examples: "His sphere of activity." "He is out of action."

(noun) an organic process that takes place in the body. Synonyms: bodily process, body process, bodily function. Examples: "Respiratory activity."

(noun) (chemistry) the capacity of a substance to take part in a chemical reaction. Examples: "Catalytic activity."

(noun) a process existing in or produced by nature (rather than by the intent of human beings). Synonyms: natural process, natural action, action. Examples: "The action of natural forces." "Volcanic activity."

(noun) the trait of being active; moving or acting rapidly and energetically. Synonyms: activeness. Examples: "The level of activity declines with age."