Fifth is the ordinal form of the number five. Fifth or The Fifth may refer to: Fifth Amendment to the United States Constitution, as in the expression "pleading the Fifth" Fifth Avenue Fifth column, a political term Fifth disease, a contagious rash that spreads in school-aged children Fifth force, a proposed force of nature in addition to the four known fundamental forces Fifth of July (New York), historic celebration of an Emancipation Day in New York Fifth (Stargate), a robotic character in the television series Stargate SG-1 Fifth (unit), a unit of volume formerly used for distilled beverages in the U.S. 1st Battalion, 5th Marines The fraction 1/5 The royal fifth (Spanish and Portuguese), an old royal tax of 20%.