~거든 (geo-deun) – 1. that’s why (you know) 2. if
1. Many sites or people would tell you that when ~거든 is placed at the end, it would have the meaning of “because”.
For an English speaker, though, it does not make any sense to place a “because” at the end of the sentence.
Therefore, I feel that it’s more appropriate to define ~거든 as “that’s why, you know” when placed at the end of a sentence.
I added a “you know” behind because usually when you use ~거든, it’s like mentioning a fact that is supposedly known between the parties involved in the conversation. It is quite similar to ~잖아 in this respect.
Example: 나 오늘 학교로 가서 공부해. 다음 주에 시험이 있거든.
I went to school and study today. There’s a test next week that’s why (you know).
2. Now, if you place ~거든 in the middle of a sentence, it has a similar meaning as ~(으)면, which means “if” or “when”.
Note that the two different meanings of ~거든 is very different when placed at different parts of the sentence.
Example: 시장에 싼 생선이 있거든 사 줘.
If there is cheap fish at the market, buy it for me.
