Definition of apokalupsis:

602 apokaluqiv apokalupsis ap-ok-al'-oop-sis

An uncovering, removal of a covering. Source: Thayers Greek-English Lexicon of the New Testament, 1889 edition

Apocalypse (two Greek words, apokalupsis, and apokalupto meaning approximately the same thing) Literally, it means the removal of a covering or a veil. God often provides the interpretation of Scripture within Scripture. There is one Scripture that gives us the key to the word, veil. Hebrew 10:19-20 says, Having therefore, brethren, boldness to enter into the holiest by the blood of Jesus, By a new and living way, which he hath consecrated for us, through the veil, that is to say, his flesh; The apocalypse is the removal of the veil of our flesh. In Scripture, it is both progressive and an end-times sudden event.

On Line Bible Lexicon:

AV-revelation 12, be revealed 2, to lighten + 1519 1, manifestation 1, coming 1, appearing 1; 18

1) laying bear, making naked

2) a disclosure of truth, instruction

2a) concerning things before unknown

2b) used of events by which things or states or persons hitherto withdrawn from view are made visible to all

3) manifestation, appearance

Luke 2:32 A light to lighten <602> the Gentiles, and the glory of thy people Israel.
Romans 2:5 But after thy hardness and impenitent heart treasurest up to thyself wrath against the day of wrath and revelation <602> of the righteous judgment of God;
Romans 8:19 For the earnest expectation of the creature waiteth for the manifestation <602> of the sons of God.
Romans 16:25 Now to him that is of power to stablish you according to my gospel, and the preaching of Jesus Christ, according to the revelation <602> of the mystery, which was kept secret since the world began,
1 Corinthians 1:7 So that ye come behind in no gift; waiting for the coming <602> of our Lord Jesus Christ:
1 Corinthians 14:6 Now, brethren, if I come to you speaking with tongues, what shall I profit you, except I shall speak to you either by revelation <602>, or by knowledge, or by prophesying, or by doctrine?
1 Corinthians 14:26 How is it then, brethren? when ye come together, every one of you hath a psalm, hath a doctrine, hath a tongue, hath a revelation <602>, hath an interpretation. Let all things be done to edifying.
2 Corinthians 12:1 It is not expedient for me doubtless to glory. I will come to visions and revelations <602> of the Lord.
2 Corinthians 12:7 And lest I should be exalted above measure through the abundance of the revelations <602>, there was given to me a thorn in the flesh, the messenger of Satan to buffet me, lest I should be exalted above measure.
Galatians 1:12 For I neither received it of man, neither was I taught it, but by the revelation <602> of Jesus Christ.
Galatians 2:2 And I went up by revelation <602>, and communicated to them that gospel which I preach among the Gentiles, but privately to them which were of reputation, lest by any means I should run, or had run, in vain.
Ephesians 1:17 That the God of our Lord Jesus Christ, the Father of glory, may give to you the spirit of wisdom and revelation <602> in the knowledge of him:
Ephesians 3:3 How that by revelation <602> he made known to me the mystery; (as I wrote afore in few words,
2 Thessalonians 1:7 And to you who are troubled rest with us, when the Lord Jesus shall be revealed <602> from heaven with his mighty angels,
1 Peter 1:7 That the trial of your faith, being much more precious than of gold that perisheth, though it be tried with fire, might be found to praise and honour and glory at the appearing <602> of Jesus Christ:
1 Peter 1:13 Wherefore gird up the loins of your mind, be sober, and hope to the end for the grace that is to be brought to you at the revelation <602> of Jesus Christ;
1 Peter 4:13 But rejoice, inasmuch as ye are partakers of Christ's sufferings; that, when his glory shall be revealed <602>, ye may be glad also with exceeding joy.
Revelation 1:1 The Revelation <602> of Jesus Christ, which God gave to him, to shew to his servants things which must shortly come to pass; and he sent and signified it by his angel to his servant John: