This is the 15829th most frequent Korean word.
봤던
"봤던" means "that I/someone saw" or "had seen."
In this sentence, 봤던 functions as a modifier, describing a past action of watching the movie.
저는 지난주에 영화관에서 봤던 영화를 정말 좋아했어요.
I really liked the movie I watched at the cinema last week.
Here, 봤던 is used to refer to an action in the past, serving as an adjective to specify the book referenced.
그가 책상 위에 두었던 책을 다시 읽고 싶어했어요.
He wanted to read again the book that he had placed on the desk.
In this case, 봤던 adds context about an encounter in the past, modifying the noun 'person'.