1. a person or party who intervenes in a legal proceeding
Usage: legal
2. someone who comes between parties in a dispute to help resolve it

Examples

• The court allowed the environmental group to join the case as an intervener.
• Several interveners filed briefs supporting the plaintiff’s position.
• The union acted as an intervener in the contract dispute.
• As an experienced intervener, she helped both sides reach an agreement.
• The judge questioned the intervener’s standing in the lawsuit.
• The intervener’s testimony proved crucial to the case outcome.