名詞 capstone:

1. a final touch; a crowning achievement; a culmination
   同義詞：finishing touch, copestone
2. a stone that forms the top of wall or building
   同義詞：copestone, coping stone, stretcher

cap.stone

n.（名詞）
The top stone of a structure or wall.
拱頂石，壓頂石，頂層石：建筑物或墻的最上面一層石頭
The crowning achievement or final stroke; the culmination or acme.
頂點(diǎn)：登峰造極的成就或最后一次成功的努力；終極或極點(diǎn)