the answer given does not seem to make sense
How would you use this word in the "he's the best" sense? Αυτός/ή/ό είναι κορυφή;
There is a sentence like that in the course, but it's more common to say "αυτός είναι κορυφαίος" or αυτός είναι στην κορυφή".
There is word "korifey" (корифей) in Russian, it means extra professional, top expert
So can this also mean the top of something? Like Ο παππούς μού βλέπει την κορυφή για το βουνό?
Yes, that would be "η κορυφή του βουνού", though. It needs the genitive case, as it is the top of something, as you said.
Brill, thanks! The genitive case makes my brain hurt!
Grandfather means the same thing as grandad so why was I marked wrong saying grandad instead of grandfather??
I don't why my answer was refused as it is exactly what i wrote