1. to sue someone in return, especially as a defendant suing the plaintiff in the same case
Usage: legal term; third person singular present tense of 'countersue'

Examples

• The defendant countersues the plaintiff for defamation.
• After being sued for breach of contract, the company countersues for unpaid invoices.
• She countersues her former employer in the same lawsuit.
• The contractor countersues for damages after the client refuses to pay.
• When accused of negligence, the driver countersues the other party for injuries sustained.