The OUD is a four-letter stringed instrument that is commonly referred to as the Arab lute. It is a fretless lute-type instrument that is believed to have originated in the Middle East and North Africa. The SITAR is a five-letter stringed instrument that is also related to the OUD. It is a plucked string instrument that is used in Hindustani classical music. The mandolin is an eight-letter stringed instrument that is related to both the OUD and the SITAR. It is a fretted instrument that is often used in folk and classical music. The OUD is also sometimes referred to as an OUD, which is a three-letter stringed instrument.