swelled head
US /swɛld hɛd/
UK /swɛld hɛd/

1.
우쭐함, 자만심
a person who has an exaggerated opinion of their own importance, ability, or attractiveness
:
•
After winning the award, he got a bit of a swelled head.
상을 받은 후, 그는 약간 우쭐해졌다.
•
Don't let success give you a swelled head.
성공이 너를 우쭐하게 만들지 마.