The Collaborative International Dictionary of English v.0.48:

Quadruplicate \Quad*ru"pli*cate\, v. t. [imp. & p. p.
   Quadruplicated; p. pr. & vb. n. Quadruplicating.] [L.
   quadruplicatus, p. p. of quadruplicare, fr. quadruple?
   fourfold. See Quadruplex.]
   To make fourfold; to double twice; to quadruple.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Quadruplicate \Quad*ru"pli*cate\, a. [L. quadruplicatus, p. p.]
   [1913 Webster]
   1. Fourfold; doubled twice; four times repeated; as, a
      quadruplicate ratio, or a quadruplicate proportion.
      [1913 Webster]

   2. (Math.) Raised to the fourth power. [R.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

quadruplicate
    adj 1: having four units or components; "quadruple rhythm has
           four beats per measure"; "quadruplex wire" [syn:
           quadruple, quadruplicate, quadruplex, fourfold,
           four-fold]
    n 1: any four copies; any of four things that correspond to one
         another exactly; "it was signed in quadruplicate"
    v 1: reproduce fourfold; "quadruplicate the bill"

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "quadruplicate":
   Photostat, Xerox, biquadrate, biquadratic, clone, copy,
   counterpart, ditto, double, dupe, duplicate, duplication,
   facsimile, fourfold, hectograph, make four, manifold, microcopy,
   microfilm, mimeo, mimeograph, model, multigraph, multiply by four,
   quadrable, quadrigeminal, quadruple, quadruplex, reduplicate,
   repetition, replica, replicate, replication, representation,
   reproduce, reproduction, stat, tetraploid, trace, transcribe,
   triplicate