Lexical Definition

‎διάδημα‎ diádēma (dee-ad'-ay-mah) diadem G:N-N
from a compound of ‎διά‎ and ‎δέω‎

crown.

Usage: 2 forms in 7 verses
Form Translated As     In Verse(s)
διαδήματα royal crowns Rev.12.3Rev.13.1Rev.19.12
διάδημα a diadem LXX.Esth.8.15LXX.Isa.62.3
diadem LXX.Esth.1.11LXX.Esth.2.17

Abbott-Smith

διάδημα, -τος, τό (< διαδέω, to bind round), [in LXX for כֶּתֶר (as Es 1:11), etc. ;]
the band round the τιάρα of a Persian king; a diadem, the badge of royalty: Re 12:3 13:1 19:12.†
SYN.: στέφανος, the badge of "victory, of valour, of nuptial joy, of festal gladness " (but v. M, Th., i, 219; cf. DB, i, 530, 604).

Abbott-Smith References

Book Refs
Ezra 1:11
Revelation 12:3 · 13:1 · 19:12

Liddell-Scott-Jones

διάδημα, ατος, τό,

(διαδέω) band or fillet: especially band round the τιάρα worn by the Persian king, [Refs 5th c.BC+]; by his successors, [Refs 2nd c.AD+]; by kings generally, [LXX+1st c.BC+]

__II Ὀσίριδος δ., ={ἅλιμος}, Ps.[Refs 1st c.AD+]