Definition of fundamental :
1. A leading or primary principle, rule, law, or article, which serves as the groundwork of a system; essential part, as, the fundamentals of the Christian faith.
2. Pertaining to the foundation or basis; serving for the foundation. Hence: Essential, as an element, principle, or law; important; original; elementary; as, a fundamental truth; a fundamental axiom.
thorough, vital, innate, wakeless, extreme, organic, positive, necessary, constitutive, axiomatic, unfathomed, important, cardinal, of import, key, primitive, perfect, total, heavy, principal, structural, superficial, ultimate, original, significant, primordial, native, constitutional, be, rudimentary, unplumbed, first harmonic, theoretical, supporting, crucial, profound, vestigial, natural, fundamental frequency, major, first, radical, primaeval, implicit in, primeval, incidental, surface, sound, thoroughgoing, unsounded, requisite
intrinsic (part of speech: adjective)
bottom (part of speech: adjective)
pure (part of speech: adjective)
basic, irreducible, blameless, angelic, primal, pure, aboriginal, immaculate, faultless, primary, undiluted, purebred, basal, honorable, elemental, unadulterated, spotless, uncluttered, innocent, unsullied, undefiled, unblemished, elementary, sinless, guiltless, simon-pure, stainless, monolithic, prime, nascent, essential, austere, clear, stark, unadorned, white, unalloyed, virtuous, chaste, bare, decent, clean, atomic, untarnished, untainted, plain, indivisible, formative, foundational, simple
severe (part of speech: adjective)
crisp, demanding, icy, blunt, Spartan, obdurate, intense, oppressive, grim, acute, exacting, caustic, strict, authoritarian, dry, abrupt, inflexible, lean, stiff-necked, harsh, frosty, prudish, acerbic, cool, sharp, dour, cutting, unbending, piquant, censorious, stringent, brusque, imperial, critical, short, raw, severe, astringent, bleak, brisk, strait-laced, obstinate, precise, intolerant, rigid, ascetic, rigorous, spare, uncompromising, meticulous, disciplined, curt, keen, hidebound, tart, acrimonious, relentless, correct, puritanical, gruff, Draconian, stern, chilly
united (part of speech: adjective)
- Is it wrong to desire in the man you are to marry that fundamental passion that makes the world go around? - "Star-Dust A Story of an American Girl", Fannie Hurst.
- After years of experience I find I cannot go back upon the knowledge that I acquired on the very first occasion of experience- that energy is a fundamental principle of the mystery. - "The Prodigal Returns", Lilian Staveley.
- A very competent and obliging French critic has said that it is impossible for any Frenchman to agree with me exactly in my estimate of La Fontaine, and probably there is no better instance than La Fontaine of the fundamental difference of conception of poetry which corresponds to the English channel. - "A Short History of French Literature", George Saintsbury.