1. Anciently a head-band or fillet worn as a hadge of royalty; anything worn on the head as a badge of royalty or sovereign dominion; a crown; sovereign power.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• diaet,
• diate,
• datem,
• diden,
• dioades,
• diaed,
• itdem,
• diesem,
• diagam,
• diadic,
• siadem,
• xiadem,
• ciadem,
• fiadem,
• riadem,
• eiadem,
• duadem,
• djadem,
• dkadem,
• doadem

• deader,
• diodon,
• didion,
• deaden.

The adjective form of the word "diadem" is "diademed".

The plural of the "diadem" can be the "diadems".

The singular of the "diadem" can be the "diadem".