cornerstone, linchpin, centerpiece, lynchpin, bedrock, integral, pillars, mainstay, backbone, underpinning, touchstone, fulcrum, component, crown jewel, hallmark, focal point, sine qua non, lodestone, part, plank, boon, holy grail, prerequisite, catalyst, staple, embodiment, element, cements, vanguard, key, death knell, capstone, underpinnings, facet, centrality, solid, bulwark, precursor, leitmotiv, leitmotif, universal, complements, bolsters, changer, jewel, paramount, definer, heralds, consociational, forerunner, crown jewels, anathema, symbol, wellspring, tenet, landmark, vestige, hinges, buzzword, foundation, precondition, masterstroke, springboard, framework, revivification, bismarckian, panacea, prime mover, lifeblood, guidepost, bridgehead, fundament, theme, achilles heel, epitome, groundwork, preeminence, antithesis, watchword, powerhouse, reinvigoration, buttresses, signifier, fertile crescent, primacy, fallback, blueprint, continuation, intrinsic, cradle, perfectibility, quintessence, telos, polestar, rebirth, meshes, cog, hub, testament, stumbling block, reaffirmation, outgrowths, pivot, crossroad, denominator, impetus, point, premise, clement, crossroads, prop, ques, question, mediating, pivotal, problematic, important, latter, problematical, allimportant, analogous, building, challenging, evolving, interactional, mediational, overdetermined, paradoxical, puzzling, semiotic, socializing, soteriological

coign, coigne, quoin

coign, coigne, gothic arch, quoin, stater

arch

building block

headstone