Definition of "capstone"

capstone

noun
plural capstones
1. Any of the stones making up the top layer of a wall; a coping stone.
2. (figurative) A crowning achievement, culmination or finishing touch.
  Quotations
  “You see, I’ve never had a girl friend,” I added, by way of topping the obelisk of silliness with the capstone of fatuity.
  1904, Guy Wetmore Carryl, Far from the Maddening Girls, chapter 5
  Success of the Apollo program has been the capstone to a series of significant accomplishments for the United States in space in a broad spectrum of manned and unmanned exploration missions and in the application of space techniques for the benefit of man.
  1969, The Post-Apollo Space Program: Directions for the Future, NASA
verb
third-person singular simple present capstones, present participle capstoning, simple past and past participle capstoned
1. (transitive) To complete as a crowning achievement; to top off.
  Quotations
  Capstoning a decade's worth of linked short stories, The Quiet War (2008) was a vivid and tense novel about a solar system sliding into conflict.
  2012, Keith Brooke, Strange Divisions and Alien Territories, page 23
2. (transitive, US, military, informal) To train in the Capstone Military Leadership Program.
  Quotations
  “Capstoned” units are now able to train and plan in peacetime with the command with which they will fight in wartime.
  1981, Army Reserve Magazine, volumes 27-28, page 24