apex
Pronunciation: /ˈeɪpɛks/
noun ( plural apexes or apices /ˈeɪpɪsiːz/)
- 1the top or highest part of something, especially one forming a point: the apex of the roof figurative the central bank is at the apex of the financial system
- Geometry the highest point in a plane or solid figure, relative to a base line or plane.
- Botany the growing point of a shoot.
verb

Origin:
early 17th century: from Latin, 'peak, tip'