the fundamental assumptions from which something is begun or developed or calculated or explained;
"the whole argument rested on a basis of conjecture"
a stone in the exterior of a large and important building; usually carved with a date and laid with appropriate ceremonies
a stone at the outer corner of two intersecting masonry walls
- The archaeologists unearthed a cornerstone bearing a Greek inscription.
- Indeed, it has come to be the cornerstone of modern thinking on international trade.