third party
noun [ C, usually singular ]
ukus LAW
a third person or organization less directly involved in an activity or in a legal case than the main people or organizations that are involved:
30% of the units that we sell are actually sold by third parties.
Shareholders may authorize a third party, such as a bank or employer, to make investments directly to their Fund accounts.
In road accident cases, the plaintiff can bring a third party in as a second defendant.
INSURANCE
in an insurance contract, a person who is not the insurance company or the insured person, but who will receive money if they suffer loss or damage caused by the insured person:
The policyholder is covered if they cause injury or damage to a third party.