From The Collaborative International Dictionary of English v.0.48 [gcide]:
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.
[1913 Webster]
The speculative line of demarcation, where obedience
ought to end and resistance must begin, is faint,
obscure, and not easily definable. --Burke.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
demarcation
n 1: the boundary of a specific area [syn: limit,
demarcation, demarcation line]
2: a conceptual separation or distinction; "there is a narrow
line between sanity and insanity" [syn: line, {dividing
line}, demarcation, contrast]