1. People or things that are extremely impressive, exciting, or successful; something that causes a sensation.
Usage: informal; often used in sports or entertainment contexts
2. Members of a radical faction of the Democratic Party in New York during the 1840s who opposed the conservative Hunkers.
Usage: historical; U.S. political history

Examples

• Last night's game was one of the barnburners of the season.
• The concert was a real barnburner—the crowd went wild.
• Those two playoff matches were absolute barnburners.
• The new action film is shaping up to be a barnburner at the box office.
• The barnburners pushed for more radical reforms in the party.
• That was a barnburner of a performance by the lead actor.