It is a word that derives from the same root as or, meaning light, and indicates the seven-branched candelabrum, another symbol of Judaism.
It was located in the "nomadic" sanctuary built by Moses for the Ark of the Covenant; it was fueled by olive oil. It subsequently formed part of the sacred furnishings of the Temple of Jerusalem, so much so that the first depiction of the Menorah appears on the Arch of Titus in Rome, which celebrates precisely the destruction and looting of the Jewish Sanctuary.
Source: "Gli ebrei questi sconosciuti" by Elena Loewenthal