Source : Webster's Revised Unabridged Dictionary (1913)

Denier \De*ni"er\, n.
   One who denies; as, a denier of a fact, or of the faith, or
   of Christ.

Denier \De*nier"\, n. [F. denier, fr. L. denarius a Roman silver
   coin orig. equiv. to ten asses, later, a copper, fr. deni ten
   by ten, fr. the root of decem ten; akin to E. ten. See {Ten},
   and cf. {Denary}, {Dinar}.]
   A small copper coin of insignificant value.

         My dukedom to a beggarly denier.         --Shak.

Source : WordNet®

denier
     n 1: a unit of measurement for the fineness of silk or nylon or
          rayon; "with an evening dress one wears 10 denier
          stockings"
     2: any of various former European coins of different
        denominations
     3: one who denies