Cetra, a Latin word borrowed from Greek, is an Italian descendant of κιθάρα (cithara).
The cithara was a stringed musical instrument, constructed in wood and similar to the lyre, with a larger harmonic case.
The instrument spread from ancient Greece, where it was played by professional citaredi, to Rome and Corsica.
[2] In the Renaissance, the term 'cetra' came to signify a pear-shaped instrument with a flat sound-board and a long neck, whose pairs of metal strings were plucked.
In Monteverdi's opera L'Orfeo (1607, libretto by Alessandro Striggio) Orpheus refers to his instrument as a Cetra (e.g. in the aria "Qual honor di te fia degno, mia cetra onnipotente", act 4).