ㄹ지언정

Even if that were so

It concedes a strong point and then insists on the other side regardless: even if you make a mistake, you can carry on; even if other people call it nonsense; even if smokers do get lung cancer. It is emphatic and bookish, at home in speeches and written argument rather than in chat, where you would say 아도 or 어도 instead. The clause after it is always the part the speaker really means.

Register: bookish and rhetorical