1. angles or corners that point inward in a geometric shape or structure
Usage: geometry; architecture
2. indented or recessed parts of a coastline, boundary, or fortification
Usage: geography; military

Examples

• The fortress design included several reentrants to provide defensive advantages.
• The coastline’s reentrants created natural harbors for fishing boats.
• Engineers measured the reentrants in the building’s floor plan.
• The map clearly showed the reentrants along the national border.
• Military strategists studied the reentrants in the enemy’s defensive line.
• The polygon contained multiple reentrants that complicated the area calculation.