우물 안 개구리 같다 · 우물 안 개구리였다
a frog in a well; someone with a narrow view of the world
Example
해외에 나가 보니 제가 우물 안 개구리였다는 걸 알았어요.
When I went abroad, I realized I'd been a frog in a well.
Word parts
A frog in a well thinks the sky is only as big as the opening.
Good to know
Usually self-critical or a gentle jab: 우물 안 개구리처럼 살다 'to live with blinkers on.'