| Underlying (a.) Lying under or beneath; hence, fundamental; as, the underlying strata of a locality; underlying principles. Thesaurus Entries 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 |