Cacumen, apex, culmen (6)
I believe the answer is:
vertex
(Other definitions for vertex that I've seen before include "Top, apex" , "Crown, apex" , "Corner (of triangle)" , "where sides meet" , "Highest point" .)
I believe the answer is:
vertex
(Other definitions for vertex that I've seen before include "Top, apex" , "Crown, apex" , "Corner (of triangle)" , "where sides meet" , "Highest point" .)