Nah, I wouldn't say a drop in teleconverter in a lens makes it a zoom lens, the zoom bit is the continuous movement between focal lengths.

I suppose even with just two focal lengths, the focal length can be "varied" which is the normal definition of zoom, but I have never heard the term used that way.

My point is the difference is a difference of terminology not in functionality. A zoom system is one that can achieve multiple focal lengths with the same setup, and in that sense the iPhone 7 plus has a 'discrete' zoom, just like for example, microscopes, or telescopes with different magnifications, or leica's tri-Elmar lenses. (Leica doesn't call them zooms because in the world of Leica primes are the standard, but I don't see why you wouldn't.)

If you define zoom as the physical action of sliding a piece of glass to achieve different focal lengths in a lens, then a digital zoom, by that definition is also not a zoom.

Now, the iPhone is not using a teleconverter, which is something that is added to the lens, but a different lens plus sensor alltogether to create the effect of a zoomed image. And this is the point where the old definitions break down; is a camera the sensor or is a camera the device that creates the picture? I think it is the latter, and in that sense I think iPhone 7 plus does have a 'discrete' zoom.

I agree it's only a matter of terminology - just like Teslas "Autopilot".

"Optical zoom" has always meant continuously variable optical focal length. That doesn't mean there is a clear definition, but there is room for confusion using it in this context.

In binoculars there is quite a difference between "dual magnification binoculars" with a switch, and "zoom binoculars" which allow for continuous change.

I'd be completely happy with the use of "2x discrete optical zoom" here - it removes all confusion.

It's not. Teleporting from point A to B is not same as walking from A to B.