1. diadem - Noun
2. diadem - Verb
Originally, an ornamental head band or fillet, worn by Eastern monarchs as a badge of royalty; hence (later), also, a crown, in general.
Regal power; sovereignty; empire; -- considered as symbolized by the crown.
An arch rising from the rim of a crown (rarely also of a coronet), and uniting with others over its center.
To adorn with a diadem; to crown.
Source: Webster's dictionaryAccording to a widespread belief, Antony had once offered a diadem to Caesar. Source: Internet
According to Suetonius, this caused consternation: the ceremony required Titus to wear a diadem, which the Romans associated with monarchy, and the partisanship of Titus's legions had already led to fears that he might rebel against his father. Source: Internet
The influence of some Persian symbols of a star within a diadem, or the eight-spoked Buddhist wheel (see the coins of the Indo-Greek king Menander I with this symbol) have also been suggested. Source: Internet
Now that the isolated frontier worlds were connected by the new stringline network, they could become self-sufficient, without paying exorbitant tribute to the Diadem Michella. Source: Internet
Later, Ravenclaw's diadem is found to be one of Voldemort's Horcruxes and has been hidden in the Room of Hidden Things by Voldemort. Source: Internet
On others, the spokes can have a more "flame-like" shape, more indicative of the representation of a star within a diadem. Source: Internet