A person taking part in a transaction or contract; a person or entity directly involved in a lawsuit. aggrieved party.A party whose pecuniary, personal, or property rights passive have been negatively affected by the actions of another or by a court's ruling. See also aggrieved. indispensible party. See indispensible party. necessary party.A party whose interests will be affected by his or her close connection to the case and who should be included if feasible, but whose absence would not req...