A reference thAT doesn' t actually lead anywhere. In C and some other languages, a pointer thAT doesn' t actually point AT anything valid. Usually this happens because it formerly pointed to something thAT has moved or disappeared, e.g. a heap-allocATed block which has been freed and reused. Used as jargon in a generalisATion of its technical meaning for example, a local phone number for a person who has since moved is a dangling pointer. [Jargon File]