septenarius

noun

sep·​te·​nar·​i·​us ˌsep-tə-ˈner-ē-əs 

plural septenarii ˌsep-tə-ˈner-ē-ˌī 

-ē-ˌē

: a verse consisting of seven feet especially in Latin prosody

Word History

Etymology

Latin, from septenarius of seven, from septeni seven each, from septem seven

First Known Use

1706, in the meaning defined above