1. Medieval nautical charts or maps showing coastlines, ports, and navigation routes, typically used by sailors and merchants.
Usage: plural of portulan; historical; nautical

Examples

• Medieval sailors relied on portolans to navigate the Mediterranean Sea safely.
• The museum's collection includes several well-preserved portolans from the 14th century.
• Portolans were among the most valuable possessions of trading ships during the Renaissance.
• These detailed portolans showed compass roses and detailed coastal features.
• Historians study portolans to understand ancient maritime trade routes.