noun

• (originally rhetoric) A rhetorical device in which a series is arranged in ascending order.
  "Ye haue a figure which as well by his Greeke and Latine originals […] may be called the marching figure […] and goeth as it were by ſtrides or paces; it may aſwell by called the clyming figure, for Clymax is as much to ſay as a ladder,[…]"
• (obsolete) An instance of such an ascending series.
  "[…]Expressions for the whole Climax of sensibility[…]"
• (narratology) The culmination of a narrative's rising action, the turning point.
  "As a trafficker in climaxes and thrills and characterization and wonderful dialogue and suspense and confrontations, I had outlined the Dresden story many times."
• (now often) A culmination or acme: the last term in an ascending series, particularly:
  "In the accomplishment of this, they frequently reach the climax of absurdity."

verb

• (ambitransitive) To reach or bring to a climax (in any sense).
  "Huntsman starts out with a vision of Theron that’s specific, unique, and weighted in character, but it trends throughout toward generic fantasy tropes and black-and-white morality, and climaxes in a thoroughly familiar face-off."