The word “Rapture” isn’t found in most modern Bibles. Then again, neither is the word “Trinity” but that doesn’t stop us from understanding the Triune Nature of God the Father, God the Son and God the Holy Spirit.
The Latin root of the word “rapture, which is “rapio” is, however, found in the Latin Vulgate rendering of 1 Thess. 4:17. This is actually a translation of the Koine Greek verb “harpazo” which means “caught up” or “taken away”. This Greek verb is only used in two places in the New Testament, in 1 Thess. 4:17 and Acts 8:39, which I list below.
“And when they were come up out of the water, the Spirit of the Lord caught away (Greek harpazo) Philip, that the eunuch saw him no more: and he went on his way rejoicing. 40 But Philip was found at Azotus: and passing through he preached in all the cities, till he came to Caesarea.”
The idea of the rapture is very easy to see, even if the word “rapture” is not actually used.
As you correctly point out, “Trinity” is not found in the Bible, but scripture points exactly to a Triune God.
“Rapture” also is not found in the Bible, but unlike “Trinity”, the scriptures when taken in full context dispute this teaching completely.
“In context” is the underlying truth here.
God Bless