Resentment (also called ranklement or bitterness) is a mixture of disappointment, anger and fear. It comprises the three basic emotions of disgust, sadness and surprise—the perception of injustice. As the surprise of injustice becomes less frequent, so too fades anger and fear, leaving disappointment as the predominant emotion. So, to the extent perceived disgust and sadness remain, the level of disappointment also remains. Resentment can be triggered by an emotionally disturbing experience felt again or relived in the mind. When the person feeling resentment is directing the emotion at himself or herself, it appears as remorse.
Robert C. Solomon, a professor of philosophy at the University of Texas at Austin, places resentment on the same continuum as anger and contempt, and he argues that the differences between the three are that resentment is anger directed toward a higher-status individual; anger is directed toward an equal-status individual; and contempt is anger directed toward a lower-status individual.
Resentment is not one of Paul Ekman's six basic emotions (surprise, disgust, happiness, sadness, anger, and fear).
The word originates from French "ressentir", re-, intensive prefix, and sentir "to feel"; from the Latin "sentire". The English word has become synonymous with anger and spite.