Antonym of "Megalomania"

Question

Is there a single word that means roughly the opposite of "Megalomania"?

I tried separating the word in to parts, and finding opposites of the individual parts, and the word I came up with was Micromania. But looking that up led to a definition very different from the opposite of megalomania, so now I'm stuck again.

Working off of this definition of megalomania: "delusion about one's own power or importance", What word means "delusion about one's own (perceived or actual) lack of power or importance", especially when it's to the severity of being a psychological disorder.

EDIT: After reviewing the answers so far, and playing around with adding prefixes and suffixes to existing words, something else I came up with that somewhat describes what I'm looking for is Autonihilism. Nihilism being the belief that everything in life or in the world is meaningless or worthless, while the "auto-" prefix narrows the focus from the whole world or all of life down to just ones-self. But I was hoping to find a word already in use, rather than one I created myself (and I'm not entirely certain that "Autonihilism" actually means what I described it to mean, except as far as I get to choose what my own created words might mean. But the description might still help others understand more clearly what I'm looking for)

EDIT 2: Comments regarding "abjectness" led me on a search through Thesaurus entries until I found "Apathy". A person with the condition described by the word I'm searching for might not consider their situation to be abject, merely a fact, just like a megalomaniac might not recognize the abjectness of their megalomania. The apathetic indifference of the affected individual to their own condition, simply treating it as a fact of life, is relevant. An outside observer might consider their condition to be "abject" in severity, while the individual themselves would not. In this sense, it's very different from something like abjectness or depression, where the affected individual might very well recognize the harm that comes to them from the condition. The word "Apathy" itself seems to relate to what is going on around the individual, while the word I'm looking for relates to the individual's view of the individual themselves, and so doesn't quite fit, when used alone.

Answer 1

You can say that person has an inferiority complex.

From the Wikipedia article:

An inferiority complex consists of feelings of not measuring up to standards, a doubt and uncertainty about oneself, and a lack of self-esteem. It is often subconscious and is thought to drive afflicted individuals to overcompensate, resulting either in spectacular achievement or extremely asocial behavior.

Answer 2

Impostor Syndrome

The imposter syndrome is a psychological term referring to a pattern of behavior where people doubt their accomplishments and have a persistent, often internalized fear of being exposed as a fraud. Not an actual disorder, the term was coined by clinical psychologists Pauline Clance and Suzanne Imes in 1978, when they found that despite having adequate external evidence of accomplishments, people with imposter syndrome remained convinced that they don’t deserve the success they have.

Source: Psychology Today

Answer 3

Meekness

Merriam Webster Dictionary's definition:

the quality or state of being meek : a mild, moderate, humble, or submissive quality

I've heard it defined casually (in a sermon) as

not abusing one's own power, or not using one's own power unnecessarily

(eg, not exceeding the speed limit, even when it is perfectly safe to do so), which would be a great antonym to Megalomania, but I can't find a dictionary definition that states it quite so succinctly.

Note the difference here between "meek" and "weak" is that the former has power (or potential), but the latter does not.

Answer 4

The previous answers perhaps better encompass all aspects of that particular definition of megalomania, but as a third, albeit narrower, option, there is the concept of "learned helplessness" in psychology.

However, this speaks mostly to one's perceived lack of power rather than a lack of self-esteem, although the two are correlated to an extent (such as through depression).

Answer 5

In a sense you're looking for a word for 'delusional feeling of omni-impotence'. As it turns out, there's a word for it...but it's probably not what you seek.

If a person is feeling completely worthless and powerless then the word that describes the person's state is (a type of) depression.

A person can also vary between (megalo-)mania and depression, in which case they'd be suffering from bipolar disorder (previously manic depression).

Answer 6

You could consider defeatist.

Defined by Dictionary.com as:

a person who surrenders easily or is subject to defeatism.

and Vocabulary.com:

someone who is resigned to defeat without offering positive suggestions

Having a defeatist attitude means that you give up before you've even started, like the runner who is so convinced he's going to lose the race that he doesn't even bother to go to the starting line.

From defeatism:

an attitude of accepting, expecting, or being resigned to defeat - Merriam Webster

a way of thinking or behaving that shows that you expect to fail - Cambridge Dictionary

Answer 7

Enfeebled narcissist: https://www.psychologytoday.com/us/blog/the-mysteries-love/201906/vulnerable-vs-grandiose-narcissism-which-is-more-harmful

Talks about the differences which megalomaniac is pretty similar to grandiose narcissist. This Article compares and contrasts the opposite. It shows how (as expected) opposites are more similar than you might expect and hot shots who think way too highly of themselves secretly are insecure inside.

If it had to be one word then: narcissism (narcissism diagnosis allows for either vulnerable/enfeebled type or grandiose type which is maybe called megalomaniacal) or self-enfeeblement (weakness in this case of self) depressed doesn't seem to be the correct antonym diagnosis since the depressed are often just lethargic/can't get enough rest --also OP specified that depressed doesn't work) this is more similar to narcissism. The narcissist thinks they are special because they are especially less important.

As the authors from the above study seem to conclude (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5601176/):

From this study, it can be concluded that grandiose and vulnerable (hypersensitive) narcissism are not distinct traits, but rather different manifestations of the same phenomenon, which aligns well with clinical theories of narcissism. Whether individuals actually display grandiose or vulnerable narcissism at a subclinical level depends on intro-/extraversion, a more basal personality trait.

Grandiose Narcissism which can pretty much be referred to as Megalomania and Vulnerable Narcissism are both close to identical they have the same underlying drivers/while the behavior sometimes differs they're pretty much the same it's why the same person who says "I have a great brain" is also very sensitive to people/media/everyone saying he's stupid and blames them in other words he seems hypersensitive as well as grandiose what's for sure is that they are a narcissist.

Vulnerable or enfeebled narcissists are characterized as being overly sensitive/quiet/not wanting to get to much attention to a pathological extent. People who are suffering from the disorder are overly insecure and probably unlikely to negotiate on their own behalf because they view themselves as worthless.