Egotism (noun)

1. The tendency to think of oneself as the center of attention.
2. The habit of talking about oneself excessively.
3. The practice of exaggerating one's own importance or achievements.

Origin:

From the latin word "ego" meaning "i" and the suffix "-ism" indicating a state of mind or belief. it entered the english language in the 19th century.

Examples:

1. His egotism made him unpopular among his colleagues.
2. Her egotism was evident in the way she constantly talked about herself.
3. His egotism led him to overestimate his abilities.
4. Many found her egotism off-putting.
5. His egotism made it difficult for him to work well with others.