The phrase "spare room" refers to an extra room in a house that isn't being regularly used, often left empty or available for different purposes. Full definition
Do councils have the power — and the stomach — to resist the coalition's controversial spare room subsidy? (totalpolitics.com)
If your resume is just one page long, you might want to spare room for more important information than what your career objective is. (blog.kickresume.com)
If you really believe in your book and have a lot of spare room, you can pay to get a large quantity of your book printed. (hubpages.com)