Extended Strong's Greek Lexicon (Abbott-Smith based)
diadem
Usage: διάδημα, -τος, τό (διαδέω, to bind round), [in LXX for כֶּתֶר (as Est.1:11), etc. ;] the band round the τιάρα of a Persian king; a diadem, the badge of royalty: Rev.12:3 13:1 19:12.† SYN.: στέφανος, the badge of "victory, of valour, of nuptial joy, of festal gladness " (but see M, Th., i, 219; cf. DB, i, 530, 604). (AS)