The Collaborative International Dictionary of English v.0.48:
Revelation \Rev`e*la"tion\, n. [F. r['e]v['e]lation, L.
revelatio. See Reveal.]
1. The act of revealing, disclosing, or discovering to others
what was before unknown to them.
2. That which is revealed.
(a) The act of revealing divine truth.
(b) That which is revealed by God to man; esp., the Bible.
By revelation he made known unto me the mystery,
as I wrote afore in few words. --Eph. iii. 3.
4. Specifically, the last book of the sacred canon,
containing the prophecies of St. John; the Apocalypse or
Book of Revelation or The Revelation of Saint John.