The term 'ZITHER's cousin' refers to two stringed instruments, the LYRE and the HARP. The LYRE is a four-stringed instrument that has been used since ancient times in Greece and other parts of the Mediterranean. It is typically played with a bow or plucked with the fingers. The HARP is also a four-stringed instrument, but it is larger than the LYRE and is usually played with the hands. Both instruments are related to the ZITHER, which is a type of stringed instrument that is played by plucking the strings with the fingers.