Swollen head is a phrase used to describe someone who is arrogant or excessively self-important. There are several synonyms that can be used to describe this behavior, including conceited, egotistical, narcissistic, prideful, and pompous. People who exhibit these behaviors often have an exaggerated sense of their own importance and tend to belittle others. They may also be intolerant of criticism and have difficulty taking constructive feedback. It is important to recognize these behaviors and avoid emulating them, as they can interfere with personal and professional relationships. Instead, strive for humility and a willingness to learn from others.