*Revelation.
It’s an old Catholic thing to distinguish between revelation (the entire bible) and the Apocalypse of John (the last book.)
"The Revelation of Jesus Christ, which God gave unto him, to shew unto his servants things which must shortly come to pass; . . ."
Apo (away from) + kaluptoh (to hide, to veil) = to unveil
Apokalupsis = an act of unveiling = revelation
Revelation is good enough for most English-speaking Bible students, and they don't need a Greek-English lexicon to get it. No one, including Romanists, customarily refers to the Book, the Bible (from biblos), as The Revelation.
If you want to, go ahead, but everyone will be confused until you "correct" him/her.