하도 ~아서/어서 · 하도 ~(으)니까
so (much), too (much), giving a reason
Example
하도 피곤해서 수업 중에 잠이 들었어요.
I was so tired that I fell asleep in class.
Word parts
Probably from Middle Korean 하다 'to be many, great'.
Good to know
Always followed by a reason clause like -아서/어서; it never ends a sentence on its own.
Related words