If I have the choice between "decaying orbit", "we are getting closer and closer to the sun" and some word I never heard before, I pick decaying orbit.
It might not be a 100% accurate, but it's easy to understand what is meant. And if that's not enough for you, think of the poor guy who said it.
He just fled a killingfield that saw his entire battlegroup torn to pieces. As he said, he's the last conscious member of the bridge crew, probably a bit woozy too from all the radiation and at the very least close to panicking.
If you were in his situation, would you go to find a dictionary to find out what the perfect term for that screwup up position you are in is, before setting of the emergency call? Would you spend even half a second thinking about it, as long as any potential listener get's the general meaning?