The Collaborative International Dictionary of English v.0.48:

Dialectic \Di`a*lec"tic\, n.
   Same as Dialectics.
   [1913 Webster]

         Plato placed his dialectic above all sciences.
                                                  --Liddell &
                                                  Scott.
   Dialectic

The Collaborative International Dictionary of English v.0.48:

Dialectic \Di`a*lec"tic\, Dialectical \Di`a*lec"tic*al\, a. [L.
   dialecticus, Gr. ?: cf. F. dialectique. See Dialect.]
   1. Pertaining to dialectics; logical; argumental.
      [1913 Webster]

   2. Pertaining to a dialect or to dialects. --Earle.
      [1913 Webster]

WordNet (r) 3.0 (2006):

dialectic
    adj 1: of or relating to or employing dialectic; "the
           dialectical method" [syn: dialectic, dialectical]
    n 1: any formal system of reasoning that arrives at the truth by
         the exchange of logical arguments
    2: a contradiction of ideas that serves as the determining
       factor in their interaction; "this situation created the
       inner dialectic of American history"

Moby Thesaurus II by Grady Ward, 1.0:

53 Moby Thesaurus words for "dialectic":
   Aristotelian logic, Boolean algebra, Ramistic logic, airing,
   algebra of classes, algebra of relations, analysis, buzz session,
   canvassing, colloquium, conference, consideration, debate,
   debating, deliberation, dialectics, dialogue, discussion,
   disputation, doctrine of inference, doctrine of terms,
   epistemological logic, examination, exchange of views,
   experimental logic, forensic, formal logic, forum, investigation,
   joint discussion, logic, logical analysis, logical discussion,
   logics, logistic, material logic, mathematical logic,
   open discussion, open forum, panel discussion,
   propositional calculus, psychological logic, psychologism, rap,
   rap session, review, seminar, set theory, study, symposium,
   town meeting, treatment, ventilation