The assets, systems, and networks, whether physical or virtual, whose incapacitation or destruction would have a debilitating effect on security, national economic security, public health or safety, or any combination thereof. -- adapted from Department of Homeland Security (DHS 2010, 46)
DHS. 2010. Department of Homeland Security Risk Lexicon, 2010 edition. Accessed on 11 September 2012. Available at http://www.dhs.gov/xlibrary/assets/dhs-risk-lexicon-2010.pdf.
This term is discussed in a resilience context. That is also the context in which the DHS Risk Lexicon was written.