He is generally credited with coining the term "unidentified flying object", to replace the terms "flying saucer" and "flying disk" - which had become widely known - because the military thought them to be "misleading when applied to objects of every conceivable shape and performance."
This is where the road to the discovery of what UFOs are basically becomes a detour down the wrong path. The Air Force felt the terms "flying saucer" and "flying disk" were misleading. The problem is they replaced it with an even more misleading term, UFO. The reason is that it presumes Extra Terrestrial spacecraft FLY.
What the Earthlings don't realize is the possibility there are Humanoid Extra Terrestrials Living Among Us (HETLAU). The ET and HETLAU have a plan to disclose their presence here on Earth but prior to that, they can't allow the Earthlings to figure out what is going on. So by containing the Earthlings minds with the terms "ET" and "UFO", this restricts the Earthlings' comprehension levels.
The term "ET" restricts the Earthlings because it keeps them from looking for HET (Humanoid Extra Terrestrials) or, more importantly, Humanoid Extra Terrestrials Living Among Us (HETLAU). Currently, Earthlings only search outer space looking for "ET".
The term "UFO" keeps the Earthlings looking for a vehicle from outer space that has flown here from another planet. What the Earthlings don't realize is you can technically FLY from another planet to Earth. So by using the term "UFO", the Earthlings have basically remained in a loop ever since Edward Ruppelt first coined the term.
No one in the aeronautical, astronautical, or military aviation sectors has come forward and explained to the Earthlings that the vehicles are using Vectored Levitation, or Vectating, to transit a star system and travel back and forth to Earth. So just like Earthlings use the term Fly or Flying, Extra Terrestrials use the term Vectate or Vectating which is a porpheme for vectored levitation.
Essentially just like Earthling man had to make the jump from ballooning to flying, man will have to make the jump from flying to vectating. As long as he still uses the term UFO to comprehend Extra Terrestrial spacecraft though, he will never figure out exactly what is going on - which is exactly what the HETLUA want.
This makes you wonder, was Edward Ruppelt a HET? We will obviously never get corroboration on that, so it is just something worth considering, but you cannot pursue it. What is interesting is how the military became the so-called experts at searching for Extra Terrestrial spacecraft yet they are able to accurately deny every single sighting that has ever occurred.
Once you realize the overall plan is for disclosure, you can realize they are never going to actually confirm one because that would become disclosure in and of itself. They may even lean towards saying it might be but that they are not sure. Only when the HETLUA running the place are ready for total disclosure according to their secret agenda will we start being informed as to the possibility of UFOs really existing.
At that point, as society becomes more technically aware of what they really are as spacecraft and how they operate, will they be able to look back and see how the term UFO held us back as a society. Once you are aware of this ahead of time you can begin to really see what is going on without having to wait with everyone else for disclosure.