Here's a remark from a web site which I daren't mention here.
The radio altimeter is often erroneously described as a "radar altimeter". In fact it doesn't use radar principles beyond the fact that it responds to reflected signals.
I think that's what I was saying. OK, I accept that some 50s/60s kit may not fit that bill; but the guy who invented RadAlts did it before Radar was even thought of.
Conclusion, just call it a RadAlt and everyone's happy.