Source : Webster's Revised Unabridged Dictionary (1913)

Basis \Ba"sis\, n.; pl. {Bases}. [L. basis, Gr. ?. See {Base},
   n.]
   1. The foundation of anything; that on which a thing rests.
      --Dryden.

   2. The pedestal of a column, pillar, or statue. [Obs.]

            If no basis bear my rising name.      --Pope.

Source : WordNet®

basis
     n 1: a relation that provides the foundation for something; "they
          were on a friendly footing"; "he worked on an interim
          basis" [syn: {footing}, {ground}]
     2: the fundamental assumptions from which something is begun or
        developed or calculated or explained; "the whole argument
        rested on a basis of conjecture" [syn: {base}, {foundation},
         {fundament}, {groundwork}, {cornerstone}]
     3: the most important or necessary part of something; "the
        basis of this drink is orange juice" [syn: {base}]