Good evening AbdiyEL,
"The great day of the Lordis near—near and coming quickly." - Zephaniah 1:14
"Let all who live in the land tremble, for the day of the Lord is coming. It is close at hand—a day of darkness and gloom, a day of clouds and blackness. Like dawn spreading across the mountains a large and mighty army comes, such as never was in ancient times nor ever will be in ages to come." - Joel 2:1-2
"Wail, for the day of the Lord is near; it will come like destruction from the Almighty. Because of this, all hands will go limp,every heart will melt with fear. Terror will seize them, pain and anguish will grip them; they will writhe like a woman in labor. They will look aghast at each other, their faces aflame." - Isaiah 13:6-8
"The revelation from Jesus Christ, which God gave him to show his servants what must soon take place." - Rev.1:1
"Blessed is the one who reads aloud the words of this prophecy, and blessed are those who hear it and take to heart what is written in it, because the time is near." - Rev.1:3
"Now, brothers and sisters, about times and dates we do not need to write to you, for you know very well that the day of the Lord will come like a thief in the night. While people are saying, “Peace and safety,” destruction will come on them suddenly, as labor pains on a pregnant woman, and they will not escape."
The day of the Lord spoken of by the OT prophets, as well as in the book of Revelation, are referring to the same time of God's wrath against mankind, also referred to as "the hour of trial" and "the great day." This time of God's coming wrath is neither an hour nor a day in length, but is a phrase designating a period of time in which God's wrath will take place.
Regarding this time of wrath, what both the OT prophets and the book of Revelation have in common, is that this time of wrath, the day of the Lord is referred to as "soon taking place" and "the time is near." Now, being that the day of the Lord, the wrath of God has yet to take place, it should move the reader to reconsider the meaning of those phrases, for it certainly couldn't be referring to our understanding of being either a day, week, month or year away. For 2800 years or so have passed since making reference to that day being near or shortly to take place.
Since the gathering of the church is apart of the day of the Lord and in fact what initiates it, the reference to being near is synonymous with the Lord's return which has always been imminent for both the OT prophets and the apostles. Therefore, the meaning of "the day of the Lord" is that it is always near, about to happen, on the horizon, looming, in the workings, etc. The phrase "is near" or "is close at hand" is referring to the day of the Lord, the time period of God's wrath, as always being imminent.
The information contained in the book of Revelation regarding the seals, trumpets and bowl judgments, are a detailed account of the day of the Lord, the wrath of God. 2800 years later we are still saying that the day of the Lord is near, about to take place. The only difference between believers today vs. the OT prophets and the apostles, is that we can say with certainty that the day of the Lord is approaching quickly and that because we are seeing all of the signs. We are seeing the stage being set for that time of God's wrath and the reign of the antichirst.
The word "Rapture" is from the Latin "Rapio" which has the same meaning of the Greek word "harpazo" which is the word used in 1 Thes.4:16:
"For the Lord himself will come down from heaven, with a loud command, with the voice of the archangel and with the trumpet call of God, and the dead in Christ will rise first. After that, we who are still alive and are left will be [caught up] together with them in the clouds to meet the Lord in the air.
Harpazo/Rapio is defined as "properly to seize by force; snatch up, suddenly and decisively, to seize, catch up, snatch away."
Harpazo is the same word used when Paul said that he was "caught up" to the third heaven. And is the same word used when Philip was "snatched away" from the Eunuch. It is also the same word used to describe the male child of Rev.12:5 being "caught up" to God and to his throne. So yes, the word is in deed there in the scripture.
In reference to 1 Thes.4:16-17, based on the rest of the context, the meaning is that when the Lord apppears, believers will be caught up to meet Christ in the air in fulfillment of John 14:1-3 where the Lord will then take the entire group back to the Father's house (heaven).