means A jeweled, semicircular ornamental headpiece worn at the front of the head, smaller than a full crown and typically worn by women on formal occasions.

from From Latin tiara, borrowed from Greek tiára, which named the tall, ornate headdress worn by ancient Persian kings and nobles. The Greeks likely picked the word up from a Persian source, though its deeper roots are uncertain. So the word traveled from the towering peaked caps of Persian royalty into the delicate jeweled arc we know today — the headgear shrank, but the air of royalty stayed.