1. The property that ensures that the actions of an individual or an institution may be traced uniquely to that individual or institution. 2. In information systems (IS,) the process of tracing IS activities to a responsible source. 3. In COMSEC, the principle that an individual is entrusted to safeguard and control equipment, keying material, and information and is answerable to proper authority for the loss or misuse of that equipment or information. 4. The property that ensures that the actions of an entity may be traced to that entity.