Action: Intentional behaviour.

A person may do many kinds of things that are not intentional in the sense that they are not willed and done to achieve a certain end. These are not actions: What a person does is an action if and only if the person did what he did on purpose, generally to obtain by it a certain end, or at least to bring this end closer to realization.

Note this does not at all imply that what one intents by one's actions will in fact be achieved, since one may have all manner of misconceptions, or be unlucky if one's beliefs are factually adequate.