What term is used to describe information that could cause serious damage to national security if disclosed without authorization?

The term that designates information capable of inflicting serious damage to national security if disclosed without proper authorization is known as "Top Secret." This classification is the highest level of security and is reserved for information that, if made public, could cause exceptionally grave harm to the national defense or foreign relations of the United States.

While "Secret Classification" and "Confidential Information" refer to lower levels of classified information, they do not encompass the severity of damage associated with top-secret data. "Secret" pertains to information that could cause serious damage, while "Confidential" is used for information that could cause some harm but is not as severe as what is classified as "Secret." "Restricted Data" specifically relates to nuclear-related information and is a separate category under national security regulations.

Thus, understanding these classifications reveals that "Top Secret" is the most appropriate term for information that, if disclosed, could lead to significant harm to national security.