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: Webster's Revised Unabridged Dictionary (1913)