This is the 8765th most frequent Korean word.
갈음했다
"갈음했다" means "replaced" or "substituted."
Here, '갈음했다' is used to show the act of exchanging an old item (car) for a new one, emphasizing replacement.
그들은 오래된 차를 새 차로 갈음했다.
They substituted their old car with a new one.
In this instance, '갈음했다' describes the act of substituting a formal event (meeting) with a casual one (gathering), indicating a change in mode.
회의를 비공식 만남으로 갈음했다.
They replaced the meeting with an informal gathering.
In this sentence, '갈음했다' is used to indicate the replacement of one task (homework) with another (project), implying substitution.