To demarcate means to mark the boundaries or limits of something, making clear where one thing ends and another begins. When a farmer demarcates their property with a fence, they're showing exactly where their land stops and their neighbor's starts. When a teacher demarcates the play area from the parking lot with painted lines, students know precisely where they can safely run and play.

The word comes from marking borders or boundaries, and you'll often see it used when people need to establish clear divisions. A country might demarcate its territory with border markers. A library might demarcate the quiet study zone from the collaborative work area. In your own room, you might demarcate your study space from your relaxation space by arranging furniture differently in each area.

Demarcation (the noun form) refers to these boundaries themselves. A line of demarcation is the actual boundary that separates two areas or groups. Scientists demarcate different climate zones on maps. Sports fields have clear demarcations showing where players can and cannot go. As people say, good fences make good neighbors, because clear demarcation prevents confusion and conflict about whose responsibility is what.

The word emphasizes clarity and definition: when you demarcate something, you remove any doubt or confusion about where divisions lie.