Authors frequently refer to things in “the bottom drawer.” It may actually be a box in the closet or a CDR in the back of the box, but it is where we keep our projects that are dead in the water. Maybe we got partway through and something horrifically just like it showed up on the book racks: these evil accidents of fashion happen. Maybe the idea didn’t work out, and we decided not to throw good time after bad, so we walked away from it. Maybe it went around to every possible publisher and just didn’t sell. The problem may not have been in the book, but in publishing fashion. Sometimes we are writing the books of ten years ago, and sometimes the market isn’t ready for what we’re writing and sometimes it’s just the wrong spot in a cycle.
The bottom drawer is a place of cobwebs and dust. The “back burner,” on the other hand, is a place to keep things warm and bubbling. It’s often where we keep ideas that haven’t quite jelled yet, possibly for decades. We may have gotten interested again in the idea from reading our own idea books, and this may be the project to work on after the current one. In the meantime, we collect some research now and then or draw some maps or do some conlang work for an invented world. We may have written nothing on it, or it may be a partial needing more thinking-out.
As a writer, your ideas and words are what you have to sell. It makes good sense both economically and emotionally to leave only incurable juvenalia in your bottom drawer.