Synonyms of fundamental

1 Syllable

main, key, first, root, ought, must, keyer

2 Syllables

vitals, prime, axioms, stapler, natal, radix, simplex, virtual, inbuilt, crucial, right-hand, plasmic, bottom, primal, central, biotic, inwrought, precept, pointful, mainer, centric, theorem, in-built, axiom, needful, smallest, builtin, headmost, major, basal, tester, littlest, righthand, grass-roots, vital, axial, theorems

3 Syllables

inherent, jesuitic, seminal, centroidal, unfleshly, germinal, underlying, systemic, paramount, incipient, integrant, essentials, amoebic, supporting, rudiment, primordial, initial, committal, cardinal, principium, constituent, minimal, cellular, sustaining, life-or-death, principal, native, radicle, capitals, component, organic, radices, ingredient, essential, needfulness, primary, integral, intrinsic, bottom-line, doctrine, principle, radical, integrals, rhizome, element, capital, radixes, ingrained, substratal, structural, savage, decretion

4 Syllables

elemental, suprahuman, foundational, underived, nonmaterial, unphysical, necessities, original, discarnate, inceptive, requisite, bottomline, axiomatic, coal-and-ice, name-of-the-game, significant, necessity, requirement, rudimental, primitive, necessary, necessaries, unevolved, theoretical, substrative

5 Syllables

supermundane, supranatural, supramundane, meat-and-potatoes, anatomical, metaphysical, exploratory, unalienable, preliminary, rudimentary, constitutional, initiatory, elementary, desideratum, pre-requisite, applicative, indispensable, apothegmatic, constitutive, axiological

6 Syllables

undeniability

7 Syllables

inevitability, indispensability, inevitabilities