The Collaborative International Dictionary of English v.0.48:

Tripartite \Trip"ar*tite\, a. [L. tripartitus; tri- (see Tri-)
   + partitus, p. p. of partiri to part, to divide. See Part,
   v. i.]
   1. Divided into three parts; triparted; as, a tripartite
      leaf.
      [1913 Webster]

   2. Having three corresponding parts or copies; as, to make
      indentures tripartite. --A. Smith.
      [1913 Webster]

   3. Made between three parties; as, a tripartite treaty.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tripartite
    adj 1: involving three parties or elements; "a tripartite
           treaty"; "a tripartite division"; "a three-way playoff"
           [syn: tripartite, three-party, three-way]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "tripartite":
   deltoid, three-cornered, three-dimensional, three-footed,
   three-pronged, three-sided, triangular, triangulate, triarch,
   trichotomous, tricorn, tricornered, tricuspid, trident, tridental,
   trifid, triflorate, triflorous, trifurcate, trigonal, trigonoid,
   trigrammatic, trihedral, trilateral, trimerous, triparted,
   tripodic, triquetral, triquetrous, trisected



Bouvier's Law Dictionary, Revised 6th Ed (1856):

TRIPARTITE. Consisting of three parts, as a deed tripartite, between A of
the first part, B of the second part, and C of the third part.