"그런데, 그렇지만, 그런데다가" * 그런데 - 그렇다 (so it is) + ~ㄴ데 (ending for "when something is happening...", a background for what follows). - So it means "and", "and then", "with that", or "that's not all", to continue with what was just mentioned. * 그렇지만 - 그렇다 + ~지만 (ending for "even if that is so", contradicting or contrasting with what was just said) - It is like English "but", "however", "even then", etc. * 그런데다가 - 그렇다 + ~ㄴ데 + 다가 (on top of what was said; adding to that). - It is literally "adding to what was mentioned", so "on top of that", "not only that", or "furthermore". 그런데 (shortened to 근데) is a light and smooth "and", as compared to 그리고 which is heavier and for enumeration. Likewise, 그렇지만 (shortened to 그치만) is a smooth "but", as compared with the heavier and emphatic 그러나. 그런데다가 (shortened to 근데다가) is similar to 거기다가 / 게다가 ("adding to that"). - 어제 집에 손님이 왔어. 그런데 그 사람이 경찰 서장이래. => We had a visitor at my home yesterday, and he was none other than the police chief. - 걔는 XX 대학 지원에서 떨어졌대. 그렇지만 YY 에는 됐어. => He is said to have been rejected at the XX university, but he got acceptance from YY. - 친구네 집 사업이 망했어. 그런데다가 엄마는 암에 걸렸어. => My friend's family business failed. On top of that his mother has a cancer.