from The Century Dictionary and Cyclopedia
- n. The plate of pure gold worn on the linen miter of the Jewish high priest.
Sorry, no etymologies found.
Polycrates, Bishop of Ephesus, writing about A.D. 190, speaks of St. John's tomb in that city, and says that he wore the _petalon_, the high priest's mitre used in the Jewish
Greeks called it, therefore, not only the born or blooming thing, but the spread or expanded thing -- "[Greek: petalon]."
It is derived from the Modern Greek _petalon_, horse-shoe, if that, indeed, is not borrowed from the Romany.