Not being used or occupied; available for use. She kept a spare key under the doormat in case she ever got locked out.
Thin or lean in build or appearance. The spare figure of the marathon runner was evident as he crossed the finish line.
Plain, simple, or unadorned in style or appearance. The room was decorated in a spare style, with only a few pieces of furniture.
Economical or frugal in use or expenditure. The writer's spare prose was both effective and engaging, leaving out unnecessary details.