Hypocrisy, sincerity, and?

Question

By definition hypocrisy is:

the practice of claiming to have moral standards or beliefs to which one's own behavior does not conform

To illustrate an analogy, hypocrisy means that you claim to be 100, when you're 50. (higher number means better)

Search for hypocrisy's antonyms and the most mentioned word I could find, was sincerity, which is:

the quality of being free from pretense, deceit, or hypocrisy.

Again, using numbers illustration, it means that if you are 50, you show 50.

I'm searching for a word to describe that you're 50, but you show 25. I can think of modesty. However, just like hypocrisy which is a negative trait (with negative connotation), I'm searching for a negative word. Modesty is good. I would enjoy being called a modest person. Maybe modest can be compared with self-confident, which is to show yourself bigger, but in a positive and welcomed way.

What word can describe showing less, but in an unpleasant way best?

Answer 1

Not a single word, but I think it fits the criteria pretty well:

sell oneself short

Wiktionary:

sell oneself short

1. To belittle oneself in judgment.

2. To avoid being acknowledged to the fullest or purest extent, as, underestimating one's abilities or image.

Cambridge

to not consider someone or something to be as valuable or good as he, she, or it deserves:

Don't sell yourself short - you've got the skills and the experience.

Inferiority complex might also work:

wikipedia:

An inferiority complex is a lack of self-worth, a doubt and uncertainty, and feelings of not measuring up to society's standards. It is often subconscious, and is thought to drive afflicted individuals to overcompensate, resulting either in spectacular achievement or extreme asocial behavior.[1] The term was coined to indicate a lack of covert self-esteem.[2] For many, it is developed through a combination of genetic personality characteristics and personal experiences.

if you're looking for one word then maybe self-abased would work:

Self`-a*based"\, a. Humbled by consciousness of inferiority, unworthiness, guilt, or shame.

Answer 2

The term false modesty refers to

Behavior that is intended to seem humble but comes across as fake and unflattering.

The term self-deprecating is also used, but it does not necessarily convey a negative tone.

Whether these terms would apply to your age examples appears to be a cultural or contextual issue.