The term 'Zither Cousins' refers to two stringed instruments, the zither and the lyre. The zither is a flat, trapezoid-shaped instrument with strings stretched across its body, while the lyre is a harp-like instrument with strings attached to a yoke. Both instruments are played by plucking the strings with the fingers or a plectrum. Both instruments have been used for centuries in various cultures around the world, and are still popular today.