1. 
[syn: ternary, treble, triple, triplex]
The Collaborative International Dictionary of English v.0.48:
Triplex \Tri"plex\, a. (Mach.)
   Having three principal operative parts or motions, so as to
   produce a three-fold effect.
   [Webster 1913 Suppl.]
WordNet (r) 3.0 (2006):
triplex
    adj 1: having three units or components or elements; "a ternary
           operation"; "a treble row of red beads"; "overcrowding
           made triple sessions necessary"; "triple time has three
           beats per measure"; "triplex windows" [syn: ternary,
           treble, triple, triplex]
Moby Thesaurus II by Grady Ward, 1.0:
20 Moby Thesaurus words for "triplex":
   deltoid, fan-shaped, tern, ternal, ternary, ternate, three,
   three-in-one, three-ply, threefold, treble, triadic, trial,
   triangular, trilogic, trinal, trine, triple, triplicate, triune