The term 'Harp Relatives' refers to a group of musical instruments that are related to the harp. These include lyres, which is a five-letter word that is one of the solutions to the crossword. Lyres are stringed instruments that have a long history, dating back to ancient Greece and Egypt. They typically have two arms connected by a crossbar, with strings stretched between the arms. Lyres were used in religious ceremonies and for entertainment purposes.