1. People who live in flat or level terrain, especially plains or lowlands, as opposed to mountainous regions.
Usage: plural of flatlander; often used by mountain residents to refer to lowland dwellers
2. Outsiders or tourists, especially from urban or flat areas, visiting a mountainous region.
Usage: informal; sometimes mildly derogatory; common in mountain communities

Examples

• The flatlanders struggled with the altitude when they first arrived in Colorado.
• Mountain guides often joke about flatlanders who underestimate the difficulty of hiking at elevation.
• Every summer, flatlanders from the city visit the Rocky Mountains for vacation.
• The locals could always spot the flatlanders by their expensive, unused hiking gear.
• Flatlanders sometimes find the steep terrain and thin air challenging.
• The town's economy depends heavily on flatlanders who come to ski and hike.