par·​ty ˈpär-tē plural: parties 1: a person or group taking one side of a question, dispute, or contest “The parties in the lawsuit reached an agreement.” 2: a group of persons organized to direct the policies of a government ”political parties with opposing agendas“ 3: a person or group participating in an action or affair “a mountain-climbing party” “a party to the transaction” 4: a particular individual: PERSON “an old party approaching 80” 5: a detail of soldiers “The infantry repulsed a landing party from the ship.” 6: a social gathering “a dinner party” “a birthday party” also: the entertainment provided for it