What Does TEMPEST Mean?
TEMPEST was a classified project of the U.S. government designed to research how some devices like computers throw off electromagnetic radiation (EMR) that could compromise data security. These emanations are often called compromising emanations or compromising emissions.
The term is used somewhat confusingly and incorrectly. Technically, TEMPEST is a coverword/codename but over the years has been used by some as an acronym for Telecommunications Electronics Material Protected from Emanating Spurious Transmissions.