keystone

['ki:stəun]

n.拱顶石, 基础, 重点

例句与用法：

The keystone in the crown of an arch.

拱顶石位于拱顶的塞缝石

A wooden frame built especially to support the sides of an arch until the keystone is positioned.

支拱板条专门用来在拱顶石放置好以前支撑拱的两边木架子

Belief in a life after death is the keystone of her religious faith.

她的宗教信仰的基础是相信死后有来生。

详细释义：

n.[C]

1. 【建】(拱门的)拱心石, 楔石

2. 主旨; 基本原则; 基础[(+of)]

Social justice is the keystone of their political program.

社会公平是他们政治纲领的基本原则。