라는 줄 알다

thought he meant X

Two readings sit under this shape. With a past tense it reports a mistaken belief about what was said or meant: 육각수라는 줄 알았잖아 'I thought you meant the band', 나는 또 짐이라는 줄 알고 'I took it to mean luggage'. With a present-tense question it is a genuine 'do you know?' — 얘가 뭐라는 줄 알아?, 'you know what he says?', used to tee up a story.

Register: casual spoken