Source : Webster's Revised Unabridged Dictionary (1913)

Ternary \Ter"na*ry\, n.; pl. {Ternaries}.
   A ternion; the number three; three things taken together; a
   triad.

         Some in ternaries, some in pairs, and some single.
                                                  --Holder.

Ternary \Ter"na*ry\, a. [L. ternarius, fr. terni. See {Tern},
   a.]
   1. Proceeding by threes; consisting of three; as, the ternary
      number was anciently esteemed a symbol of perfection, and
      held in great veneration.

   2. (Chem.) Containing, or consisting of, three different
      parts, as elements, atoms, groups, or radicals, which are
      regarded as having different functions or relations in the
      molecule; thus, sodic hydroxide, {NaOH}, is a ternary
      compound.

Source : WordNet®

ternary
     adj : 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: {treble}, {triple},
            {triplex}]
     n : the cardinal number that is the sum of one and one and one
         [syn: {three}, {3}, {III}, {trio}, {threesome}, {tierce},
          {leash}, {troika}, {triad}, {trine}, {trinity}, {ternion},
          {triplet}, {tercet}, {terzetto}, {trey}, {deuce-ace}]

Source : Free On-Line Dictionary of Computing

ternary
     
         A description of an {operator} taking three
        arguments.  The only common example is {C}'s ?: operator which
        is used in the form "CONDITION ? EXP1 : EXP2" and returns EXP1
        if CONDITION is true else EXP2.  {Haskell} has a similar "if
        CONDITION then EXP1 else EXP2" operator.
     
        See also {unary}, {binary}.
     
        (1998-07-29)