1. people or things that cause disturbance, disruption, or emotional distress
2. competitors who defeat favored opponents in sports or contests
Usage: sports

Examples

• The protesters were seen as upsetters of the peaceful demonstration.
• Those upsetters in the tournament knocked out three top-seeded players.
• The new regulations created upsetters among the business community.
• Several upsetters emerged from the qualifying rounds to challenge the favorites.
• The upsetters caused chaos at the town hall meeting.
• Nobody expected the upsetters to make it to the championship game.