adj. Describes a user interface under which "What You See Is What You Get", as opposed to one that uses more-or-less obscure commands which do not result in immediate visual feedback. The term can be mildly derogatory, as it is often used to refer to dumbed-down user-friendly interfaces targeted at non-programmers; a hacker has no fear of obscure commands. On the other hand, EMACS was one of the very first WYSIWYG editors, replacing (actually, at first overlaying) the extremely obscure, command-based TECO.
See also WIMP environment.
[Oddly enough, this term has already made it into the OED. -- ESR]