arm, back, backbone, background, backrest, basal, base, basic, basilar, basin, basis, deadline, elemental, elementary, essence, essential, essentials, foothold, footing, foundation, framework, fund, fundamental, ground, grounding, groundwork, keystone, mainstay, maintenance, pedestal, pivotal, primal, primary, primordial, radix, reliance, root, rudimentary, stake, staple, substratum, substructure,
support, trail, ultimate, vital