Updated: Aug 1
I’m not going to use a dictionary definition. I have a special interest in the understanding of emotions, and resentment is an important one due to its characteristics, its consequences, and its involvement in the development of mental disorders. I’ll try to find a description that is useful for our mental health.
Resentment is not a spontaneous emotion. It doesn’t depend on facial muscles, and it’s not universal. Meaning, it’s not one of the primary emotions that are experienced the same way by every person, like sadness, joy, surprise, disgust, fear, and anger.
It’s not a secondary emotion either. Secondary emotions are emotional reactions we have to other emotions. Secondary emotions might then be broken down further into what is known as tertiary emotions.
Warren D. TenHouten, in his book “A general theory of emotions and social life,” described resentment as a tertiary emotion that includes anger, rage, outrage, fury, wrath, hostility, ferocity, bitterness, hate, loathing, scorn, spite, vengefulness, dislike, resentment
You can read about primary, secondary, and tertiary emotions here: What are the primary, secondary and tertiary emotions?
Now that we know that resentment is an emotion that is the result of feeling several emotions before it arises, let's investigate further.
What’s the word resentment’s etymology. I believe that words carry wisdom since they were invented with a purpose and were adapted with a meaning assigned, even if after centuries they end up meaning something else.
The word originates from French "ressentir", re-, intensive prefix, and sentir "to feel"; from the Latin "sentire".
In English, the word has become synonymous with anger, spite, and holding a grudge.
The Latins invented the term to describe the act of “feeling again.” I think that’s more accurate and goes with the concept of tertiary emotions.
To feel again is exactly what I experience if I carry resentment. I feel the anger, or the injustice, to the “original” emotion, but augmented and probably “hidden” as in “I will never tell you how I feel when you do that to me”.
According to theorists like TenHouten, resentment comes after rage that comes after anger, and it can come accompanied by more anger & rage, or outrage, fury, wrath, hostility, ferocity, bitterness, hate, loathing, scorn, spite, vengefulness, dislike, and resentment.
That’s a lot of feeling! How does that manifest in the body (brain)?
Emotions are actually experiences that are associated with the activation of certain regions in the brain. There are regions in the brain, specifically in the limbic system, that are associated with each of the 6 main emotions.
Every experience has a “valence” in terms of whether it has a positive or negative reaction. If you experience joy, that is connected to a type of activation in your brain with a positive valence. The more joy, the more neurons will carry that positive valence. The more times you experience joy, the stronger that positive valence circuit of neurons will become, to the point of having an automatic response to stimuli similar to the ones you experienced before as joyful created in your brain as a default. That’s, generally speaking, how the brain learns and programs itself to react. That’s part of memory; how the brain remembers what’s important or not, what’s pleasurable, and what’s painful.
Anger is associated with activation of the right hippocampus, the amygdala, both sides of the prefrontal cortex and the insular cortex.
All that means that every time we experience resentment, we are activating the limbic brain and re-experiencing rage, which is a very strong circuit formed by the repeated activation of anger. It means that the valence of resentment is very highly negative because it involves many neurons firing up a negative response, and remembering more of that valence over and over again.
That sounds very much like trauma and traumatization: in trauma, the brain reacts automatically to any stimuli that resemble the traumatic event —or the cause of fear— in order to make sure the person doesn’t get defeated again. The only difference would be that in trauma, the person got defeated, and in resentment, the person may be accumulating anger and rage in order to avoid being defeated. If the anger is rooted in the fact that the aggravating person or situation is defeating the resented, then, is that resentment a possible indicator of trauma?
Emotions are supposed to protect us, but if the original anger didn’t protect the person, then rage appeared to be louder in the fight for protection, and then, resentment can come not as a louder way to fight back, but as an acceptance of not being capable to fight back.
So, resentment could be an emotion that carries a sense of impotence, and giving up, it will “motivate” the person to generate solutions like revenge, retaliation, annihilation, vengeance, and so forth.
Originally answered as What is resentment? at Quora