When there's no mountain left to climb and nothing but blue sky above, you know you've reached the highest peak — the apex.

Apex can mean the highest point in a literal sense, like climbing to the apex of the Eiffel Tower for a fabulous view of Paris. It also can be used to mean the highest point in a figurative sense. An actor who wins an Oscar can say she's reached the apex of her career. If you're describing more than one high point, you could add an -es to form the plural apexes, but apices would also be correct. And if you're a botanist, you'd probably use apex to describe the tip of a flower or leaf.

Definitions of apex

n the highest point (of something)

acme, peak, vertex
the part of a hat (the vertex) that covers the crown of the head
roof peak
the highest point of a roof
Type of:
extreme, extreme point, extremum
the point located farthest from the middle of something

n the point on the celestial sphere toward which the sun and solar system appear to be moving relative to the fixed stars

apex of the sun's way, solar apex
the point opposite in direction from the solar apex; the point the solar system is moving away from
Type of:
celestial point
a point in the heavens (on the celestial sphere)

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