Isn't LyX WYSIWYG ?
Personally I would say it is. (and also @vancomycin below).
Sure there is also the "WYSIWYM" category, but it's more of a pun and not broadly known.
LyX is not WYSIWYG and I'm not sure how to argue this point. What you see in the editor window doesn't look like the paginated output - it's not really up to someone's opinion to decide.
It's not the paginated output but it's close, especially compared to LaTeX code. And I believe many people understand WYSIWYG broadly as a point and click interface with visual feedback, in contrast to writing some code.