ETV or Extra Terrestrial Vehicle is the most general term used to describe what UFO and or UAP actually are. A better way to express it might be ETV is a term that describes what the users of the terms UFO/UAP think they are when they use those terms. The goal is an attempt to start actually using terms that explain what the vehicles are rather than using ambiguous terms like UFO and UAP. The evolution is:
UFO -> UAP -> ETV
First you have to realize the term ET is incorrectly formatted as Extraterrestrial. The HET have done this to prevent the UEA from realizing that ET or Extra Terrestrial can be formed from HET or Humanoid Extra Terrestrial. By making ET appear as one word it reduces the ability for society to recognize the HET form and reduces the probability they will figure out HETLAU or HET Live Among Us.
Second the term vehicle vs spacecraft denotes the ability to traverse mediums. We know that we need a vehicle that can depart an atmosphere travel through space and arrive in an atmosphere. Calling them spacecraft focuses on the intra space or within space activity whereas we need to focus on the complete inter space or from one medium transitioning through space to another medium commute.
From here the goal is to narrow the spectrum of UFO/UAP type phenomena we are trying to assess as a ETV. We basically only want a vehicle that has a pilot in order to process disclosure in a way the public can accept. Vehicles that are drones (non piloted) or phenomena like light balls are just distracting us from narrowing the focus.
With the focus specifically on vehicles what defines the Extra Terrestrial nature of them. This is where we develop new terminology to answer that with CTV (Celestial Tach One Vehicle).