Apex

the tip, point, or vertex; summit.
climax; peak; acme:
His election to the presidency was the apex of his career.
Astronomy, .
a type of international air fare offering reduced rates for extended stays that are booked in advance.
Contemporary Examples

Its placing at the apex of British life is itself a little nuts, as the Ovation series shows.
The Cult of Royal Porn Tim Teeman April 25, 2014

You thought that LeBron James had already reached the apex of cultural relevancy?
LeBroning, Macklemore, Devil Baby Attack and More Viral Videos The Daily Beast Video January 17, 2014

But the KKK actually reached its apex of influence during the 1920s.
A Brief History of Wingnuts in America; From George Washington to Woodstock John Avlon August 16, 2014

Maybe the era Michael represented, the apex of American power he sang the soundtrack for, ends here as well.
My Brush With the King of Pop Gideon Yago June 25, 2009

Just as we had the housing bubble, we now seem to be at the apex of the stainless steel bubble.
Beyond Stainless Megan McArdle October 18, 2012

Historical Examples

We have then a somewhat pear-shaped area or triangular area with the apex at the apex of the heart.
Arteriosclerosis and Hypertension: Louis Marshall Warfield

Researches in the direction of the apex have not been made recently.
Punchinello, Vol. 1, No. 12, June 18, 1870 Various

Longitudinally and horizontally, from apex to apex of the cones, was a steel deck dividing the vessel into two equal parts.
A. D. 2000 Alvarado M. Fuller

With the pointer in his hand he touched the star at the apex of the fir.
Bride of the Mistletoe James Lane Allen

Spiro was delaying their death until the workers of apex would have time to gather and witness it.
The Heads of Apex Francis Flagg

noun (pl) apexes, apices (ˈæpɪˌsiːz; ˈeɪ-)
the highest point; vertex
the pointed end or tip of something
a pinnacle or high point, as of a career, etc
(astronomy) Also called solar apex. the point on the celestial sphere, lying in the constellation Hercules, towards which the sun appears to move at a velocity of 20 kilometres per second relative to the nearest stars
noun acronym
Advance Purchase Excursion: a reduced airline or long-distance rail fare that must be paid a specified number of days in advance
(in Britain) Association of Professional, Executive, Clerical, and Computer Staff
n.

c.1600, from Latin apex “summit, peak, tip, top, extreme end;” probably related to apere “to fasten, fix,” hence “the tip of anything” (one of the meanings in Latin was “small rod at the top of the flamen’s cap”), from PIE *ap- “to take, reach.” Proper plural is apices.

apex a·pex (ā’pěks)
n. pl. a·pex·es or a·pi·ces (ā’pĭ-sēz’, āp’ĭ-)
The pointed end of a conical or pyramidal structure.
apex
(ā’pěks)
The highest point, especially the vertex of a triangle, cone, or pyramid.
Arctic Polynya Experiment