copestone

/ˈkoʊpˌstoʊn/
noun
  1. A stone that forms the top of a wall or building; a capstone.
    • The mason carefully placed the copestone on the garden wall.
    • The old bridge still has its original copestone in place.
    • Each pillar was finished with a carved copestone.
  2. A finishing touch or crowning achievement.
    • His latest invention is the copestone of years of research.
    • The final chapter serves as a copestone to the entire series.
    • Winning the award was the copestone of her career.
Antonyms
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