cornerstone

英 ['kɔːnəstəʊn] 美['kɔrnɚston]

• n. 基础；柱石；地基

1. the fundamental assumptions from which something is begun or developed or calculated or explained;

"the whole argument rested on a basis of conjecture"

2. a stone in the exterior of a large and important building; usually carved with a date and laid with appropriate ceremonies

3. a stone at the outer corner of two intersecting masonry walls