keystone, linchpin, centerpiece, lynchpin, bedrock, mainstay, hallmark, foundation, touchstone, pillars, focal point, backbone, crown jewel, integral, underpinning, groundwork, paramount, part, tenet, component, lifeblood, testament, staple, bulwark, prerequisite, framework, catalyst, blueprint, core, sine qua non, fulcrum, vanguard, boon, forerunner, antithesis, priority, landmark, precursor, watchword, recommitment, forefront, lodestone, anathema, element, epitome, embodiment, key, milestone, crown jewels, flagship, facet, spearhead, reaffirmation, complements, holy grail, vestige, death knell, pioneer, plank, capstone, launching pad, principles, culmination, commitment, founding, imperative, reinvigoration, stumbling block, litmus test, stepping stone, bastion, byword, pinnacle, contributor, outgrowth, enabler, cements, solid, exemplar, underpinnings, guidepost, byproduct, continuation, hub, achilles heel, savior, flourishing, precondition, strengthening, buzzword, proponent, rebirth, panacea, crucible, premier, relic, bolsters, impediment, jewel, legacy, stalwart, centrality, cornerstones, desideratum, rationale, foundations, prop, conundrum, premise, crux, raison, justification, problem, foundational, controversial, debated, pivotal, basic, exegetical, fundamental, sacrosanct, aforementioned, debatable, hasic, legalist, noncontroversial, outdated, pedagogic, pedagogical, timehonored, unworkable, accepted

corner, quoin

building, edifice, explanation

assumption, stone, supposition

base, basis, foundation, fundament, groundwork