apex
1. [ noun ] the highest point (of something)
Synonyms: peak acme vertex
Examples:

"at the peak of the pyramid"

Related terms: extreme_point crown roof_peak
2. [ noun ] (astronomy) the point on the celestial sphere toward which the sun and solar system appear to be moving relative to the fixed stars
Synonyms: apex_of_the_sun's_way solar_apex
Related terms: antapex celestial_point celestial_sphere
Similar spelling:   apse
  apace
  apiece
  APC
  appose
  apogee
  Apache
  appease
  Apus
  Apsu
  Apis