n. foundation, base, basis, footing, ground, groundwork, root, backdrop, backbone, bed, bottom, corner stone, fortification, fundament, ground form, hard pan, keystone, pedestal, socle, substratum, substructure, grass roots

adj. basic, bread and butter, fundamental, primary, principal, underlying, elementary, basal, abecedarian, constitutive, elemental, guiding, parent, rudimental, rudimentary, staple, working