Dumbledore said:
“There is a room in the Department of Mysteries that is kept locked at all times. It contains a force that is at once more powerful and terrible than death, than human intelligence, than the forces of nature. It is also, perhaps the most mysterious of the many subjects for study that reside there. It is the power held within that room that you possess in such quantities and which Voldemort has not at all. That power took you to save Sirius tonight. That power also saved you from possession by Voldemort, because he could not bear to reside in a body so full of the force he detests. In the end, it mattered not that you could not close your mind, it was your heart that saved you.”

He is obviously talking about love, but one line confuses me, “a force that is at once more powerful and terrible than death.” How is love more terrible than death? And what do you think love looks like when it is kept in a room?

I suppose you could say love hurts. Or something. But it also confuses me, and especially about it being in a room.  

I think Dumbledore is using the kinda archaic meaning of terrible meaning "powerful"...  ...just looked it up on merriam webster: "formidable in nature"