1. to mark the boundaries or limits of something
2. to separate or distinguish clearly between things

Examples

• The fence demarcates the property line between the two houses.
• Orange cones demarcate the construction zone on the highway.
• The treaty demarcated the border between the two nations.
• A clear line demarcates professional behavior from personal conduct.
• The river demarcates the eastern boundary of the national park.
• We need to demarcate the areas where smoking is prohibited.
• The study demarcates three distinct phases of economic development.