nomos, in music, class of traditional melodies used by ancient Greek epic singers, often with lyre accompaniment. The nomos was an important art form for professional soloists, especially in musical competitions. Nomoi were in three, five, or seven movements and originally in a single harmonia. There were no strophic repetitions.
Nomoi were also performed on the kithara (lyre) and the aulos (double-piped oboe). Best known is the five-movement nomos depicting Apollo’s victory over the dragon, played on an aulos at Delphi in 586 bc.