1. Literally, having a thickness comparable to paper; exceptionally thin. Often hyphenated when used before a noun. This knife is so sharp that it can cut vegetables into paper-thin slices. The top layer is paper thin, so be careful not to tear it.

2. By extension, quite meager, inadequate, or feeble. John is always offering some paper-thin excuse as to why he's late. The promises the new president made in her campaign were exceptional, but so far her results have been paper thin.