In the 1580s, as people began naming rhetorical techniques, they needed something to describe the apex of the action, so they borrowed the Latin word climax, which basically meant a "dramatic culmination". This came from Greek klimax, which had figurative overtones of something moving from weaker to stronger and a literal definition of "ladder". Makes sense- you're moving upwards when you go up a ladder, just like the story is. Now, because all old ladders had to be slanted against a building, it's also not too shocking that klimax comes from the Ancient Greek verb klinein, meaning "to slant". Because of Sanskrit and Latin cognates, we can further reconstruct this as deriving from Proto-Indo-European kley, meaning "to shelter" or "cover". Climax in reference to orgasms was coined in 1880 by feminist, botanist, and birth control proponent Marie Stopes, who attempted to make sex more relatable to the general public and loosen impressions of it.
Adam Aleksic, a freshman studying linguistics at Harvard University, has been described as the internet's sixth most famous etymologist. He has disturbing interests in words, vexillology, geography, board games, limericks, and law, and he loves writing about himself in the third person.
The Etymology Nerd