I suspect that this is NOT a feature of Word at all but rather of the keyboard app on the tablet. This looks like the autocorrect on my Android Tablet, which does not have Word.

I think you are on to something.
When using the tablet, if I switch to the more standard looking "on screen" keyboard, instead of the default "touch screen" keyboard, the word prediction feature goes away.

I'll check with the guy I'm helping, and see which keyboard he is using.

Thanks!