Source : Webster's Revised Unabridged Dictionary (1913)

Demarcation \De`mar*ca"tion\, n. [F. d['e]marcation; pref.
   d['e]- (L. de) + marquer to mark, of German origin. See
   {Mark}.]
   The act of marking, or of ascertaining and setting a limit;
   separation; distinction.

         The speculative line of demarcation, where obedience
         ought to end and resistance must begin, is faint,
         obscure, and not easily definable.       --Burke.

Source : WordNet®

demarcation
     n 1: the boundary of a specific area [syn: {limit}, {demarcation
          line}]
     2: a conceptual separation or demarcation; "there is a narrow
        line between sanity and insanity" [syn: {line}, {dividing
        line}, {contrast}]