Bighead (noun)

A person who is excessively proud of their own abilities, accomplishments, or intellect.

Origin:

Mid 19th century: from big + head.

Examples:

1. The new employee was quickly labeled as a bighead due to his constant boasting about his achievements.
2. The bighead's arrogance was often met with annoyance by his coworkers.
3. Despite his impressive credentials, the bighead was not well liked due to his haughty attitude.
4. The bighead was known for always taking credit for the work of others.
5. The bighead's ego was eventually his downfall, as he was unable to work effectively with others.