There are 2 main definitions of apex in English:

apex1

Syllabification: a·pex
Pronunciation: /ˈāpeks
 
/

noun (plural apexes or apices /ˈāpəˌsēz, ˈapə-/)

1The top or highest part of something, especially one forming a point: the living room extends right up into the apex of the roof figurative the apex of his career was when he hoisted aloft the World Cup
More example sentences
  • Crucks, great curving oak trunks arching from ground level to the apex of a building, were one of the classic ways in the Middle Ages of providing a basic framework for a building, and a means to support its roof.
  • The mountain range's east summit comes next and then the rocky perch that is the 3776 ft summit, the apex of the quartet of ridges.
  • The pitched roof of each shelter was 2.2 m above ground level at its apex and 1.5 m high along the sides and ends.
Synonyms
1.1 Geometry The highest point in a plane or solid figure, relative to a base line or plane.
More example sentences
  • In contrast, Blake demonstrated that a triangle with a proximal apex and distal base is the most effective shape for rowing.
  • It has an uneven shape, being wider at the apex than at the base.
  • Slopes increased from the apex to the base, although the data were more scattered at the base.
1.2 Botany The growing point of a shoot.
More example sentences
  • Excision of the apex releases lateral shoot buds; these were removed and collected as one sample.
  • Shoot apices from three plants were dissected.
  • A shoot apex was considered dead if the terminal bud was absent or if it was dark-brown in colour, dehydrated or damaged.
1.3The highest level of a hierarchy, organization, or other power structure regarded as a triangle or pyramid: the central bank is at the apex of the financial system

verb

[no object] Back to top  
Reach a high point or climax: melodic lines build up to the chorus and it apexes at the solo
More example sentences
  • In Argentina, differentiation on the basis of race starts with a color continuum apexing at ‘White,’ while ‘Black’ constitutes the base of the social pyramid.
  • Montana law, which allowed miners to pursue veins of ore that ‘apexed’ on their claims, regardless of where they led, handed judges enormous power-and enormous opportunity for corruption.
  • The hours and hours and hours of travel finally apexed with a few more hours and hours of travel which led to a couple more hours and hours of travel until I finally arrived in Seattle, the home of ‘really cold rain.’

Origin

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

Definition of apex in:

There are 2 main definitions of apex in English:

Apex2

Syllabification: A·pex
Pronunciation: /ˈāpeks
 
/

noun

[usually as modifier]
A system of reduced fares for scheduled airline flights and railroad journeys that must be booked and paid for before a certain period in advance of departure: Apex fares
More example sentences
  • There will be no change on Apex fares for South Wales customers, although there will be a rise of 2.5 per cent elsewhere.
  • Off peak tickets, including Apex, Advance and SuperAdvance, are also going up by an average of three per cent.
  • Fares will remain roughly the same with an Apex return fare at £16 for advance bookings.

Origin

1970s: from Advance Purchase Excursion.

Definition of apex in: