Which word refers to a person who is excessively proud of their achievements?

The term "vainglorious" specifically describes someone who is excessively proud of their achievements, often to the point of showing off or boasting about them. This word captures the essence of vanity and self-importance related to one's accomplishments, which is central to the question. It implies not just pride, but that the individual is overly concerned with their own image and the perception of their achievements by others.

While "arrogant," "pompous," and "egotistical" do relate to a sense of inflated self-worth or pride, they convey slightly different nuances. Arrogance suggests an attitude of superiority toward others, often implying a dismissive view of those perceived as less accomplished. Pompousness carries the connotation of being overly grand or self-important, often associated with a perceived need to impress others. Egotistical behavior indicates a focus on oneself, but it does not exclusively imply pride in achievements, instead encompassing a broader self-centered attitude.

Thus, the word "vainglorious" is the most precise descriptor for a person who takes excessive pride in their achievements, providing a clear distinction from the other terms.