THESAURUS
ab ovo, basal, basic, basilar, between the lines, bottom, cardinal, constituent, constitutive, covert, critical, crucial, cryptic, delitescent, dormant, elemental, elementary, esoteric, essential, foundational, fundamental, gut, hibernating, hidden, indispensable, latent, lurking, material, muffled, mystic, necessary, needful, obfuscated, obscured, occult, of the essence, original, possible, potential, primal, primary, primitive, radical, rudimentary, sleeping, submerged, substantial, substantive, under the surface, unmanifested, veiled, virtual, vital