Source : Webster's Revised Unabridged Dictionary (1913)

Fundamental \Fun`da*men"tal\, a. [Cf. F. fondamental.]
   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.

         The fundamental reasons of this war.     --Shak.

         Some fundamental antithesis in nature.   --Whewell.

   {Fundamental bass} (Mus.), the root note of a chord; a bass
      formed of the roots or fundamental tones of the chords.

   {Fundamental chord} (Mus.), a chord, the lowest tone of which
      is its root.

   {Fundamental colors}, red, green, and violet-blue. See
      {Primary colors}, under {Color}.

Fundamental \Fun"da*men`tal\, n.
   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.

Source : WordNet®

fundamental
     n : the lowest tone of a harmonic series [syn: {fundamental
         frequency}, {first harmonic}]

fundamental
     adj 1: serving as an essential component; "a cardinal rule"; "the
            central cause of the problem"; "an example that was
            fundamental to the argument"; "computers are
            fundamental to modern industrial structure" [syn: {cardinal},
             {central}, {key}, {primal}]
     2: being or involving basic facts or principles; "the
        fundamental laws of the universe"; "a fundamental
        incompatibility between them"; "these rudimentary truths";
        "underlying principles" [syn: {rudimentary}, {underlying}]
     3: far-reaching and thoroughgoing in effect especially on the
        nature of something; "the fundamental revolution in human
        values that has occurred"; "the book underwent fundamental
        changes"; "committed the fundamental error of confusing
        spending with extravagance"; "profound social changes"
        [syn: {profound}]