cornerstone
I
noun
backbone, base, body, cardinal point, core, corpus, critical point, crucial point, crux, essence, essential matter, exigency, foundation, frame of reference, fundamental, gravamen, groundwork, heart, highlight, key, keynote, keystone, landmark, main body, main element, main point, main thing, mainstay, major event, major part, material point, matter of concern, matter of importance, milestone, nucleus, pedestal, pivot, principal part, principle, purport, purpose, quintessence, rudiment, salient point, sine qua non, standard, substance, substantiality, support, terra firma, threshold
II
index
corpus, foundation (basis), gravamen, mainstay
Burton's Legal Thesaurus.
William C. Burton.
2006