> word processor, computer program used to write and revise documents, compose the layout of the text, and preview on a computer monitor how the printed copy will appear. The last capability is known as “what you see is what you get” (WYSIWYG; pronounced wi-zē-wig).
and
> Before word processors were available, text-editing programs offered the basic editing capabilities of word processing but without WYSIWYG. WYSIWYG depends on high-resolution bit-mapped computer graphics displays.
So encyclopaedical definition of WP puts WYSIWYG as definitive characteristic of WP from TE.