Just sufficient resources, with nothing to spare. For example, The room was furnished with just the bare necessities—bed, table, chair. This idiom uses bare in the sense of “mere, and nothing else,” a usage dating from about 1200.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.