한국어 공책

그런 such; like that; that sort of
그런하다 to be so; to be such

그런데 but; however; still, etc
그러면 (shortened form of 그렇다면 AND 그럼 is an even shorter form!) if so; in that case; if (when) it is like that, etc
그러니까 so; therefore; accordingly, etc

I don't know where the 데 comes from, but on the way to work today I suddenly realized/decided/concluded that 그러면 comes from 그런 and the vst-(으)면 form (if..then, when...then) form. Long, "If it's like that then..." Short, "If so, in that case."

This form can be shortened even further to 그럼, which is commonly used as a filler word. "OK; well; then..."

I also realized/decided/concluded that 그러니까 comes from 그런 plus vst-(으)니까 form (since A, then B; because of this) form. Long, "Because it was like that..." Short, "So, therefore, thus."

I don't know if these realizations will actually help me use the words any better, but it was cool to realize the connection on my own.

Edited: 2월15일

그래도 nevertheless, even thought
-도 form added (even though, yet, although)