This is the 4186th most frequent Korean word.
주장이다
To assert or claim.
In this sentence, '주장' refers to one's argument or claim in a discussion or debate context.
그의 주장은 매우 설득력이 있다.
His argument is very persuasive.
'주장' is used to denote the leader or captain of a team here.
팀 주장으로서의 책임을 다해야 한다.
You must fulfill your responsibilities as the team captain.
Here, '주장' conveys the act of asserting or claiming something strongly.