Cornerstone - Definition

n 1: the fundamental assumptions from which something is begun
or developed or calculated or explained; "the whole
argument rested on a basis of conjecture" [syn: basis,
base, foundation, fundament, groundwork,
cornerstone]
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