action

n. 1. Any process of doing something usually involving complex motor behaviors intended to accomplish a goal, as in the action of eating. 2. A natural process such as the action of a drug on the nervous system. 3. The initiation of a legal proceeding. 4. A particular military conflict or combat, as in “He saw action in Vietnam.” 5. An operating mechanism, as in the action of a rifle. 6. Sexual interaction, as in the phrase “looking for some action.” 7. The important activity in a particular field, as in the phrase “where the action is.”