The term '60s Sign' refers to the iconic symbol of PEACE that was popularized during the 1960s. The crossword solution for this term is 'PEACE, ' which is a five-letter word. The symbol of PEACE, which consists of a circle with three lines extending from its center, was first used in the 1950s but became widely popular during the 1960s as a sign of anti-war sentiment and the counterculture movement. It has since become a universal symbol of PEACE and is still used today.