CLUE (5) - And on her forehead a name was written: A mystery: Babylon the great, the mother of the fornications and the abominations of the earth.” (Rev 17:5, Douay-Rheims Catholic Bible)
The following quotes help to clarify the meaning of the "name written on her forehead"...
[BEGIN QUOTE] -The woman is said to have a name on her forehead (Revelation 17:5). In Rome the prostitutes in the public brothels wore upon their foreheads a frontlet giving their names. This is another vivid detail in the picture of Rome as the great corrupting prostitute among the nations. . . . .
[“A mystery: Babylon the great”] - The mystery in this case is that Babylon means Rome; the thing which the stranger does not know, but which the Christian reader does know, is that while the story is told under the name of Babylon everything relates to Rome. (Barclay) – [END QUOTE] [1]
[BEGIN QUOTE] - This inscription being written upon her forehead is intended to show that she is not ashamed of her doctrines, but publicly professes and glories in them before the nations: she has indeed a whore's forehead, she has refused to be ashamed. The inscription upon her forehead is exactly the portraiture of the Latin Church. This Church is, as Bishop Newton well expresses it, A MYSTERY of iniquity. This woman is also called Babylon the Great; she is the exact antitype of the ancient Babylon in her idolatry and cruelty, but the ancient city called Babylon is only a drawing of her in miniature. This is indeed Babylon THE GREAT. "She affects the style and title of our HOLY MOTHER, the CHURCH; but she is, in truth, the mother of harlots and abominations of the earth." [END QUOTE] [2]
END NOTES
[1] BIBLE HUB, Barclay’s Daily Study Bible – “The Fall of Rome”, Revelation 17:1-18, Accessed August 20, 2024, Web: https://biblehub.com/commentaries/revelation/17-4.html
[2] STUDY LIGHT, Clarke’s Commentary – Revelation 17:5., Accessed September 27, 2024, Web: https://www.studylight.org/commentary/revelation/17-5.html