any party to an incident, case, quarrel, etc., who is incidentally involved.
(in a two-party system) a political party formed as a dissenting or independent group from members of one or both of the two prevailing major parties.
Origin of third party
An Americanism dating back to 1795–1805
Words nearby third party
Third Market, third mate, third molar, third occipital nerve, Third Order, third party, third-party insurance, third party procedure, third-party software, third peroneal muscle, third person
But amid this widespread and sustained dissatisfaction, 2014 was a terrible year for third-party candidates.
How to Run a Statewide Campaign on $38|Michael Ames|November 12, 2014|DAILY BEAST
Are the third-party vendors mining this data for other purposes?
Your Arrest Video Is Going Online. Who Will See It?|Jacob Siegel|September 11, 2014|DAILY BEAST
In 2011, the FDIC released a report titled “Managing Risks in Third-Party Payment Processor Relationships.”
The Banks’ War on Porn Stars|Richard Abowitz, Marlow Stern|May 7, 2014|DAILY BEAST
They also make phone calls and relay data to third-party fitness apps such as MapMyRun.
These Are the Best Fitness Gadgets at CES|Megan Humphreys|January 13, 2014|DAILY BEAST
Thus, you can expect a third-party movement to emerge if Christie somehow manages to secure the 2016 GOP nomination.
Why Republicans Should Fear ‘Ready for Hillary’|Myra Adams|November 13, 2013|DAILY BEAST
All this, however, does not prove that the third-party people were not the real forerunners and founders of the Republican party.
The Abolitionists|John F. Hume
But the one man with the political vision to see the possibilities of the third-party movement, was not a member of a labor union.
'The System,' as uncovered by the San Francisco Graft Prosecution|Franklin Hichborn
The conference ended with an agreement to support a Third-Party movement directed by Jenkins.
Secret Armies|John L. Spivak
Since the Civil War, the currency question has twice given life to third-party movements.
The Boss and the Machine|Samuel P. Orth
British Dictionary definitions for third party
third party
noun
a person who is involved by chance or only incidentally in a legal proceeding, agreement, or other transaction, esp one against whom a defendant claims indemnity
adjective
insuranceproviding protection against liability caused by accidental injury or death of other persons or damage to their propertythird-party insurance