Motive » motivation

An impetus, stimulus, or drive, either internal or external, causing a person to act, an intervening process and a state of psychological arousal impelling an organism to action – an energizer of behaviour – with these forces responsible for the initiation, persistence, direction, and vigour of goal-directed behaviour, including such social forms as the need for achievement and the need for affiliation;

a rationalization, justification, or excuse given by an actor as the reason for his or her behaviour;

(see also: motivational bias)