culmination

(astronomy) The position of a heavenly body when at highest apparent altitude. For a heavenly body which is continually above the horizon, the position of lowest apparent altitude.
(geology) A high point on the axis of a fold.

noun

1. The highest point or state: acme, apex, apogee, climax, crest, crown, height, meridian, peak, pinnacle, summit, top, zenith. Informal payoff. Medicine fastigium. See high/low.
2. The condition of being fulfilled: consummation, fruition, fulfillment, materialization, realization. See do/not do, happy/unhappy.

The noun has 4 meanings:

Meaning #1: a final climactic stage
  Synonym: apogee

Meaning #2: (astronomy) a heavenly body's highest celestial point above an observer's horizon

Meaning #3: the decisive moment in a novel or play
  Synonym: climax

Meaning #4: a concluding action
  Synonyms: completion, closing, windup, mop up