Emily Dickinson Lexicon

TI-A'RA, n. [Fr. tiere; L. Sp. and It. tiara; Gr. τιαρα; Sax. tyr. See Syr. ܚܕܪ chadar, Class Dr, No. 15, and Heb. עטר atar, No. 34. From the former probably the Latins had their cidaris, and tiara from the latter; the same word with different prefixes.]

1. An ornament or article of dress with which the ancient Persians covered their heads; a kind of turban. As different authors describe it, it must have been of different forms. The kings of Persia alone had a right to wear it straight or erect; the lords and priests wore it depressed, or turned down on the fore side. Xenophon says the tiara was encompassed with the diadem, at least in ceremonials. Cyc.
2. An ornament worn by the Jewish high priest. Exod. xxviii.
3. The pope's triple crown. The tiara and keys are the badges of the papal dignity; the tiara of his civil rank, and the keys of his jurisdiction. It was formerly a round high cap. It was afterward encompassed with a crown, then with a second and a third. Cyc.