Strong’s Greek
G1428 — dodekatos
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
δωδέκατος
dodekatos — pronounced do-dek'-at-os
from 1427; twelfth:--twelfth. see GREEK for 1427
1 occurrence in the KJV.
Revelation 21:20
The fifth, sardonyx; the sixth, sardius; the seventh, chrysolyte; the eighth, beryl; the ninth, a topaz; the tenth, a chrysoprasus; the eleventh, a jacinth; the twelfth, an amethyst.