/ˈpɪnəkl/
pin·na·cle
BrE /ˈpɪnəkl/
NAmE /ˈpɪnəkl/
[usually singular]
~ of sth
the most important or successful part of sth
the pinnacle of her career
a small pointed stone decoration built on the roof of a building
a high pointed piece of rock, especially at the top of a mountain