Need-to-know: a determination made by a possessor of classified information that a prospective recipient, in the interest of security, has a requirement for access to, or knowledge, or possession of the classified information in order to perform tasks or services essential to the fulfillment of an official purpose. Knowledge or possession of, or access to classified information is not afforded to any individual solely by virtue of the individual’s office, position, or security clearance.
Non-disclosure agreement (NDA): a legal contract between at least two parties that outlines confidential materials or knowledge the parties wish to share with one another for certain purposes, but wish to restrict from generalized use. In other words, it is a contract through which the parties agree not to disclose information covered by the agreement.
Nuclear, Biological, or Chemical Weapons (NBC): weapons that are characterized by their capability to produce mass casualties. See weapons of mass destruction (WMD)