Collins COBUILD Advanced Learner's English Dictionary - dividing line

(dividing lines) 1. A dividing line is a distinction or set of distinctions which marks the difference between two types of thing or two groups. There’s a very thin dividing line between joviality and hysteria. N-COUNT: usu sing, oft N between pl-n 2. The dividing line between two areas is the boundary between them. ...people on both sides of the dividing line between Israel and the occupied territories. N-SING: oft N between pl-n