Unpopped popcorn kernels are referred to as "old maids," when found at the bottom of the popcorn bowl or popper. Alternatively, they are sometimes called "spinsters," which is another term for an old maid.
Old maid and spinster are both derogatory terms for women, "beyond marriageable age," or who have never married. The term came to refer to popcorn kernels because, like an old maid who has never had children, the kernels did not pop.
Unpopped kernels lack enough moisture to pop during the cooking process. These kernels can be saved and placed in a quart jar. When the jar is 3/4 full, add a tablespoon of water and seal the jar with an airtight lid. Shake the jar every few minutes until the kernels have absorbed the water and then store in a cool area. After approximately 3 days, the kernels can be reused.