Definition of Cornerstone
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
a stone at the outer corner of two intersecting masonry walls
a stone in the exterior of a large and important building
usually carved with a date and laid with appropriate ceremonies
the fundamental assumptions from which something is begun or developed or calculated or explained
"the whole argument rested on a basis of conjecture"