swellheaded

/ˈswɛlˌhɛdɪd/
adjective
  1. Having an exaggerated sense of one's own importance or abilities; conceited.
    • Her swellheaded attitude made it hard for her to work well with others.
    • The coach warned the team not to get swellheaded after their first victory.
    • After winning the award, he became so swellheaded that he ignored his old friends.
Antonyms