1. broad deep ocean waves caused by distant storms or earthquakes
Usage: nautical; oceanography
2. rapid spontaneous growth of public opinion or political movement
Usage: figurative

Examples

• The groundswells from the distant hurricane created dangerous surfing conditions.
• Sailors could feel the long groundswells rolling beneath their boat.
• There was a groundswell of support for the new environmental policy.
• The candidate benefited from groundswells of grassroots enthusiasm.
• Political groundswells often emerge during times of economic uncertainty.
• The oceanographer studied how groundswells travel across the Pacific.
• Community groundswells helped pass the local referendum.