A tiara (from Persian تاره tara adopted in Latin as 'tiara'^{[citation needed]}) is a form of crown. There are two possible types of crown that this word can refer to.

Traditionally, the word "tiara" refers to a high crown, often with the shape of a cylinder narrowed at its top, made of fabric or leather, and richly ornamented. It was used by the kings and emperors of some ancient peoples in Mesopotamia. The Assyrians used to include a pair of bull horns as a decoration and symbol of authority and a circle of short feathers surrounding the tiara's top. The Persian tiara was more similar to a truncated cone, without the horns and feathers but more jewels, and a conic-shaped tip at its top.