In the tradition of Western thought the word "emotion" is generally misused for feelings and sentiments -- in general, for affects. These are, in neurological and physiological terms, not emotions at all.
Aristotle's Rhetoric has a long list of irascible and concupiscence emotions in pairs, each with its opposite, such as love and hate or joy and sorrow. A similar listing and grouping is adopted by Thomas Aquinas in his Summa Theologica. Other lists are presented by Benedict Spinoza in his Ethics, Book IV, where they are called the passions and are treated in relation to human bondage and freedom. We can also find listings of the emotions or passions in Francis Bacon, Thomas Hobbes, and John Locke, and in subsequent writing by British empirical psychologists, David Hume, George Berkeley, and J. S. Mill.
A very short list of emotions is presented in the psychology of William James, where he pays tribute to Professor C. Lange, a Danish physiologist, for his contribution to a theory of emotions that came to be known as the James-Lange theory.
According to this theory, emotions are wide-spread bodily and visceral changes that are controlled by the sympathetic nervous system. This widespread neurological and physiological commotion includes such things as pupillary dilation, changes in the respiratory system and in the psycho galvanic system (electricity in the epidermis), presence of adrenaline in the blood stream, and changes in the pulse. This complex state of changes, occurring simultaneously and accompanied by bodily movements of attack and withdrawal, constitutes an emotion, strictly speaking.
With two exceptions, all emotions are alike in their visceral components, differing only in the bodily actions of attack and withdrawal. Anger or rage is one of them, and fright or fear is another. They are alike viscerally but they are differentiated in the acts of attack and withdrawal that accompany the same visceral commotion.
Two exceptions are grief, on the one hand, and sexual orgasm on the other hand, these two have no opposites. There is no emotion of joy or one of love. Most of the so-called emotions (listed and grouped by the philosophers from Aristotle, Aquinas, Spinoza, and the British empirical psychologists, until we get to the psychology of William James and to the James -- Lange theory of the emotions) are mild feeling, sentiments, or affects that involve no physiological, neurological, or visceral components.
I have little hope that people generally will give up making long lists of the emotions that fill the pages of literature. These lists belong to poetry, not to scientific physiology and neurology. The best word to use for the psychological states they refer to is the word "sentiment."
Sentiments represent the nonrational aspect of human nature, the aspect of human nature that human beings share with other animals. (See Continence and Incontinence.) The human conflict between reason and the passions that is discussed there afflicts human beings because they are like other animals, on the one hand, and unlike them, on the other. The James -- Lange theory of emotions applies to the lower animals as well as to human beings, as anyone knows who has observed a hissing and ferocious cat or a frightened rabbit.
Adler's Philosophical Dictionary (1995)
Great Ideas from the Great Books (1963)
by Mortimer J. Adler