The Greek word diadēma refers to a royal crown or diadem — a crown of sovereignty worn by kings, distinct from the stephanos (victor's wreath). It appears three times in Revelation, most powerfully in 19:12 where Christ is described returning with 'many diadems on his head,' signifying supreme royal authority over all kingdoms.
The diadēma is the crown of kingship — absolute sovereignty. In Revelation, the dragon wears seven diadems (12:3) and the beast wears ten (13:1), claiming earthly political power. But Christ wears 'many diadems' — more than all earthly kingdoms combined, the ultimate expression of universal sovereignty. Earlier, the elders cast their stephanoi (victor's crowns) before the throne (Revelation 4:10), acknowledging that even their victories belong to the King. The diadem theology of Revelation proclaims that all earthly political power is temporary and derivative; the risen Christ is the one true King whose rule will never end.