Webster’s Revised Unabridged Dictionary · 1913
Demarcation
De′mar·ca′tion (dē′mär·kā′shŭn), n. [F. démarcation; pref. dé- (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.