That would be in St. Scofield's Inspired Margin Notes:
Mat 3:16 -
Jesus
For the first time the Trinity, foreshadowed in many ways in the Old Testament, is fully manifested. The Spirit descends upon the Son, and at the same moment the Father's voice is heard from heaven.
:)
The truth of the trinity appears, but the actual word "trinity" does not.
The truth of the rapture appears (we can argue about the timing), but in English the word doesn't appear. In the Latin, it does.